2004 Porsche 996 C4S 30HP Challenge with $2,000Budget

Hello Porsche Fam, Will be upgrading a few pieces on my 04 C4S and wanted to pick your brain on what you would spend the $2,000 for Engine Performance on. Here is what I am hoping to accomplish. Wanted to get 30HP with bolt on parts hovering around 2k budget. I am keeping the stock XLF PSE mufflers on, I love the grumbling sound it makes. This is my daily driver to work(5 miles) and weekend vehicle. I do not track the car, it has 138K miles on it btw. This is just the engine/exhaust/intake performance budget. I have set aside another budget for suspension components, Clutch, IMS, RMS, semi solid motor mounts, and FF transmission inserts. Please let me know if there is something else I am missing. Here's a rear pic. List: Top Gear 200 Cell Catalytic crossover pipes. Cost $531 HP: 12 to 15 Claim Wanting these over the X-Pipe design so I can keep low end torque. Off shore brand headers. Cost $200 HP: 5-7 Claim Air Intake (K&N Cold air system or EVOMS) Cost $500 HP: 6-10 Claim IPD Plenum Cost $790 HP: 24 Website Claim GT3 82MM Throttle Body Cost $200 HP: unknown Under Drive Belt Pulley Cost $ UKN HP: unknown Total:$2,221 HP:45 to 57 est Thank you, Vincent

Counterpoint: If you aren't tracking the car, do you really need extra power? It's pretty rare on the street that you can responsibly open the taps 100% for more than a few seconds without endangering yourself and others and/or risking arrest. So is the difference between 320 hp and 350 really going to affect your enjoyment of the car $2000 worth? Furthermore are you willing to risk decreased reliability by stressing the engine more with some of these mods? I think the K&N intake is pretty universally frowned upon on here. It pulls in hotter air from inside the engine bay instead of colder air from the spoiler that the stock unit has access to, and it likely has poorer filtration. I think its main advantage is that it makes more noise, but IMO that's better done via exhaust, which it sounds like you already have taken care of. You'll also get conflicting reports on the underdrive pulley. The main risk I see with that is that you will reduce your coolant circulation. And some of the cheapo pulleys have been known to shear in half, so if you do it, buy a good one. You'll also get conflicting reports on headers and their merits. There was a thread on here recently discussing the pros and cons of the cheap ones from the land of China vs. ones that would consume almost your entire budget. Anyway, my point is you might drop $2000 into the car and be disappointed that you can't really feel much of a difference after. Even if you were tracking the car, 30 hp extra would probably only result in tenths of a second gained on lap times. Worth it? That's up to you! Personally I'd rather spend the money on something I can feel or see more readily every day, like suspension, wheels, tires, interior or exterior appearance stuff, etc.

You are not going to get those added HP numbers by stacking parts... unless you dyno tune the car. And, that can be catastrophic in the wrong tuners hands!

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I am also in the market for a new exhaust, and I have tentatively eliminated X-pipes, partly for the same reason. But if the other exhaust related things in your list provide more hp, wouldn't they also reduce low end torque for the same reason (reduced back pressure)?

I have an like new EVOMS air intake kit for sale for $400.oo shipped. Save you a little money off of that 2k target! PM me if interested, and good luck otherwise.

Your wallet will be a lot lighter and I bet the total gain is less than 20hp total probably won�t break 15. It will sound nice though. i wouldn�t put a k&n on any car I liked. If you like dirt in your engine, go for it. You want 100 hp for less than 2k, nitrous works every time. It�s also a quick ticket to kaboomtown when things go wrong.

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Hello DKraige, No don't really need extra power. Just want it breath and flow a bit better. Want to hear the PSE system roar a bit. I don't even listen to the radio at times, just the sound of the exhaust is music to my ears. I am going with the 200 Cell catalytic crossover pipes, might find some better mid range headers(any recommendations around $500?) Sticking with an air box from a 997(for aesthetics) with OEM paper air filter and staying away from the under drive pulley. Already purchased the GT3 82mm throttle body and searching for IPD plenum. My 996 air box tabs are broken off, this allows the snorkel to be loose and swings freely. My factory headers after a visual inspection has rust around the nuts and bolts, this is one reason I want to remove and replace. I haven't taken the car pass 5,500 RPM yet. Just drive around the 3-5K range when merging onto the highways. The Oklahoma roads are pretty bad, I am mostly looking out for potholes. Lucky for me, my 10min drive to work is on roads with a lot of curves and twist mostly. Yes, I have set aside monies for other items needing to be replaced as you pointed out like suspension, wheels, tires, interior or exterior appearance stuff (going to replace side markers as previous owner spray painted them black) :/ Thanks for your input, taking your advice on avoiding the K&N, pulley, and sourcing mid range headers. AnthonyGS, lol no thanks on the nitrous. Im sure you blew up a lot of Hondas with that nitrous in your time. Nein_11, I did actually give that EVOMS some thought for many months now. I saw your post. Did you do a before and after dyno run? RS10, yes I am willing to sacrifice a little lost of low end torque. Hoping the IPD plenum + GT3 82mm throttle body will make some back(I don't know) If this set up amplifies the exhaust tone and adds 15-30HP, then I am happy. Most of my OEM parts are broken anyway. 996 airbox tabs are broken, snorkel swings freely. I recently replaced the oil tube, it was throwing a CEL. OEM headers has rusty bolts & nuts. This car came from the east coast. Maybe due to salted roads in the winter. 808Bill, will be looking into this with my Indy. Dyno-ing the vehicle before and after parts installed. They are going to do my wheel alignment after the new suspension components and wheel & tires package install. I will try to follow up with pictures. My greasy hands all over the iphone while working on the vehicle. Going to do install one time over the span of 1-2 weeks. Been gathering a grocery lists of parts over the past months. September weather will be in the 70-80's hopefully, that will be my start date. Thank you again for chiming in. Much appreciated.

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I'd forego the performance mods and continue saving for these items - I'd think they would be your priority, especially the IMS bearing.

Just sit and read the forums for awhile. Do a search for performance mods. It�s all there - whether you like what you read is debatable. $2k isn�t going to get you much except a lighter bank account., but you�re welcome to have at it!

I have the 200 cell cats and they sound nice. Don't change the headers, the Porsche ones are very good. If I had $2000 for "track mods": 1. Deep sump/x51 oil baffles- all the power mods in the world won't help when you starve your bearings of oil. $500 2. AWD delete. Free 3. entry level bucket racing seat(s) - much lighter than the stock seats. $1500 Now your car is 100 lbs lighter and more durable.

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I was thinking of putting my OEM Headers back too, why do you say that?

I'd spend the $2k on good adjustable shocks and new anti roll bar bushings At 138k yours are worn out

Keep in mind the fact that HP gains from mods are not necessarily cumulative. You can’t simply add up the numbers to determine your total gain.

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How true, very true and nothing but the truth

^^+1 HP mods on NA 996s are a waste. Better cats and underdrive pulley are about all that I've seen make the slightest difference on the dyno. Everything else is nearly placebo. For laptimes, a good LSD is one of the top priority after safety and protecting the engine.

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See this thread, along with others: Yeah, I know this statement is triple hearsay, but it is interesting there are no RUF headers for the 996. If you look at the 997 headers, the x51 headers look like 996 3.6 headers...coincidence? (stock left, x51 right) Most of the posts I can find that claim power gains from stock 3.6 headers seem to be from manufacturers.

I�ve never raced a Honda but have many domestic V8 and 4cyl turbo fords. Nitrous is mad powah. I just installed the top gun 200 cell cats on my 996 C2 due to a CEL. They are a quality part for the price just remember the 200 cell cats won�t last as long as OEM. At the price, quality and speed of shipping I am quite happy. The cats included new collector gaskets and bolts too which I needed since mine were Colorado rust buckets.

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There is no similarity between these two headers that I can see.

not exactly apples to apples, but try to drive a an X51 car +25 hp There are a smattering of C4S and other C2's with that option, and all the AE cars see how it feels personally I'd throw money at the suspension, easiest way to make a 911 drive faster

Catbypass and Tune will net you the best ROI

Hello Porsche Fam, Jhbrennan=Yes, IMS, Clutch, RMS and oil change is my first priority. Budget is $1,000 Dporto=The forums is what educated me on some of the needed mods. IMS, RMS, Clutch, Suspension bushings, New Engine Mounts. If you see my picture, the rear driver side tailpipe is sagging. Possibly worn out engine mount. Strathconaman=Great point! Creating this post has saved me $1,000 from the Performance budget to put in for lighter bucket seats savings. I will be keeping the AWD however, safety issues. Deep sump x51 oil baffles, I won't be tracking the car. I am thinking the Porsche Engineers tested the OEM headers and they gave the best all around HP and torque through out the power curve? I just need to replace the rusted nuts and bolts w/o stripping or breaking them off. Lighter=will make it seem stronger/faster. Thank you for finding the RUF info. Chris(MA)=yes, I am going with FEAL coilovers. Powerflex anti roll bar bushings. At 138K they do feel a bit sloppy vs. my Boxster S (redid the whole suspension/IMS/Clutch/RMS/Brakes and my Uncle purchased the car) Dennis C=understood. Thank you. Slakker=I went with the FEAL coilovers from a previous post you commented on. I think the OP used CEIKA coilovers and you recommended FEAL. I will be getting better CATS though, staying away from under drive pulley. LSD=I have the AWD C4S, not sure how that would work out. Not going to track the car. It is my daily to work and weekend nice weather vehicle. You're in Oklahoma too, we need to hang out! AnthonyGS=I am just messing with you buddy. I am sure your domestic V8 and 4cyl turbo fords went to the moon and back with that nitrous! All of my bolts and nuts are a bit rusty, going to replace them. I found the Top Gun 200 Cell Cats from this forum and reading member's reviews. Thank you for your feedback on those. Fracture=If I can find a X51 or AE car for sale locally, I might ask to test drive. And Yes, I have a separate budget for the suspension. All that power is no good if it can't stick on the ground. Suspension will be: FEAL coilovers, Semi Solid Engine mounts(WEVO or Torque Solutions) Function First tranny insert(orange) Power Flex bushings for anti roll bar, Power flex bushings for the control arms, links, LCA (just need a 2 ton shop press) Auto Quest Motorsports=Going to my indy to dyno and seek advice on the tune. Thank you all! Might just keep the OEM headers, just replace all the rusty nuts/bolts. Searching for bucket seats to save weight, not high priority but will begin looking.

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So left is normal 996 3.6 and right is 996 X51 3.6? I recently read a thread where someone said the X51 header is the same as the 996 3.8 header, which I understood to mean exatly the same. I also read (same thread)? someone saying they had 17 (or 18?) more hp than stock with 997 headers. And since the extra displacement of the 997 3.8 would account for about 18 hp compared to our engines, that leaves 17 that comes from something else ... . My guess had always been that a lot/most of the X51s power comes from more agressive cams that provide more high end torque. So there would be more of a gap between when the low rev valve timing works well and when the high rev valve timing works well. If you search the forum, you'll find a thread about the X51 in which I made several posts (and probably started, not 100% sure now). And as I stated there, I'm not a big fan of the X51. I've driven three cars with it, and it seems to me that in the mid-range it has slow throttle response. Perhaps that's just a symptom of weaker torque, or maybe there's both weaker torque and weaker throttle response - not sure. I was probably in the minority in this view, though I was not alone. There was for instance this guy whom some of you may have heard of named Jake ... .

No, left side is stock 997 right is 997 x51 x51 looks like stock 996 3.6

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Also, from what I've been told the triangle header flanges on the 997 models are made from stamped sheet metal while the older 996 headers use solid 10mm thick flanges. Plus the diameter of the primary tubes on the x51 headers is 48mm while the non-x51 ones are 42mm.

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I would agree with this completely. My goal was throttle response in the 3-4000 rpm range. I added the Speedtech X-pipe and a tune. I am happy with the results. I would NOT say this is a noticeable hp increase.

You'll want to delete the AWD prior to the LSD just because it's free improved handling. I'm not sure how they would work together though. As for hangin out, absolutely. But you know that will significantly increase your chances of taking your car to the track, right? Especially once you get those coilovers on there. Then you are just a set of RE-71Rs (and race pads) away from the best time of your life!

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Tune means chip-tune? And Ratchet1025, Speedtech has two X-pipes. You mean the one without the cats, no?

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So 997 x51 looks like stock 996? Then what do 996 x51 headers look like?

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1) Correct...tune-->remote tuning via OBD port. Almost all tuners offer this nowadays. In retrospect, I would personally only recommend a tune with a dyno shop, so you can see the before and after changes. 2) Yes, the version without the Cats. The O2 Sensor extensions worked perfectly (no CEL). Also less mass and better sound (in my opinion).

Just get your ECU re-flashed and save about $1200 of your $2000 budget.

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the pipe diameter is larger on the x51

Not past 5500rpm yet you say, I think its time to take the long way home from work and get to know the cars full personality, its a different beast when your tickling the limiter.

Hello Porsche Fam, About to go to bed, but wanted to chime in before then. adjusted list: Top Gear 200 Cell Catalytic crossover pipes. Cost $531 HP: 12 to 15 Claim Wanting these over the X-Pipe design so I can keep low end torque.=Will be purchasing within 1-2 weeks. Off shore brand headers. Cost $200 HP: 5-7 Claim =Not going to buy headers, but our Rennlist friend Strathconaman posted x51 headers(pics below). Got me thinking about these. vs. stock 996 headers. Air Intake (K&N Cold air system or EVOMS) Cost $500 HP: 6-10 Claim =Not going with this. Going with 997 3.6 or 3.8 OEM airbox for aesthetics. Using the OEM paper filter as well. IPD Plenum Cost $790 HP: 24 Website Claim=still searching. GT3 82MM Throttle Body Cost $200 HP: unknown=Already purchased($35 bucks shipped). Looking for IPD Plenum to complete install. Under Drive Belt Pulley Cost $ UKN HP: unknown =changed my mind. Not purchasing. Stock 997 Headers(Left) and x51 headers(right) ​​​​​​ Slakker= I have too many expensive hobbies. Next thing you know, I'll be trailering my beater up to Hallet. Is that where you track often? Rachet1025=Where can I source these O2 Sensor extensions? I rather go CAT bypass to save some weight, but it will throw CEL. David993S=ECU re-flashed? Yes, going to look into this. I did not see a dyno wheel at my local indy. I may have to search a local shop around here for a dyno. Get my 200 Cell CATs on or CAT bypass if I can figure out how to bypass the CEL with those 02 Sensor extensions Ratchet is referring to. 9964runner=lol, It starts roaring in the 5K range, I let off the throttle as I am doing 80-90mph merging onto the freeway. No way do I go that fast on the in/back roads to work. I am getting all new components in the next 1-2 weeks. One of them being the IMS bearing. Not trying to blow the engine just yet. It will be pretty tempting once everything is complete, I do have to give this 300HP work commuter car some respect and be responsible. Thank you all.

As has been covered already in this thread, Porsche did a really good job of eeking as much power as possible out of the M96, meaning there are minimal things you can do to actually increase the power output from the engine, especially for under $2k. Most of the "power adders" you can buy for this car will at best move the power to somewhere else in the power band, not actually help the car make more power. The best way to "increase power" is to reduce the weight of the car. Knocking 10% off the weight of the car would theoretically equate to a 10% increase in power, so there's your 30 horses. Here are popular ways to knock the weight down: - Remove AWD - Lightweight seats - Lightweight battery - Lighter wheels - Aftermarket mufflers - Remove spare tire/tool kit - Remove rear seats - Remove anything unnecessary from the car (stereo amplifiers, floors mats, owners manual, etc.) - Remove engine coolant and oil ( I'm kidding , don't do this. Or do, but record it for us to watch)

Where can I get X51 Headers? I understand OEM 996 Headers are 42mm and X51 is 48mm correct?

From some research, that is correct. You can get them from Suncoast Porsche as one source. https://www.suncoastparts.com/product/PKX51HEADER.html

Fleabay has a bunch of different types of 996/997 headers, so if you are up for some risk-taking https://www.ebay.com/bhp/porsche-997-headers

And if you want to go full bore https://www.fabspeed.com/porsche/911-carrera-996/

wait are the 997.1 S Headers same as X51 Headers?

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Nope. See also: https://rennlist.com/forums/996-foru...ml#post6402984 Note that @jumper5836 did the 997S x51 swap onto his 996...and he just did a re-build to 4.0L...hmmmmmm.

I wonder if the heads are port matched? The size and shape look completely different to my eye.

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As I recall (when I did the math) every 100# that you remove from the car equated to a theoretical 9(something) horsepower. It's not hard to take a bunch of weight out quickly - it's the smaller increments that start getting expensive. Going off of memory here from my car: - Rear carpet pad that covers the shock towers 4# - More rear carpet was another 10# - Seats are basically boat anchors - I installed OMP HTE Carbon drivers and WRC passenger - I estimate that I took 60# out - Frunk carpet, trim and liner was like 7# - Rear seats were worth 10ish - Center console, trim, etc in the 7 or 8 range - Lightweight battery knocked 34# off the weight - Stereo and speakers are worth 20# - OZ HLT wheels were worth about 16 over stock

Shipping to the US for the top gear cats was around $100 via DHL. Packing was good and parts arrived quickly, but I�d adjust your budget accordingly.

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Removing rotating weight from the car is one of the biggest boosts you can get. Each pound of rotating mass you can remove from a wheel is essentially like removing 4 pounds of static weight. Also, switching to a lighter exhaust will save 30-50 pounds.

Oh yeah! I have Fabspeed mufflers, headers, and catless x-pipe which took some weight off.... The unsprung weight reduction is hugely beneficial - as stated above - calculated to be a 4:1 payout.

Seems Blue Chip and Capt. Obvious nailed it. Didn't JR a while back say the way to power up is by increasing displacement or go X51. Two grand ain't gonna cut it The old adage I heard was 10 lbs. = 1hp. One of the main reasons why some air cooled owners pulled out their heavy/failing AC systems. Best to lighten it. Rotating and unsprung mass make a big difference. Twice a year when the summer/winter wheel swap takes place on my other car the difference is striking. Are the twists hollow? Ti. Lugs perhaps? AGM battery, lose the spare tire and back seats. Different mufflers...it all adds up.

I'd invest in: Helmet, tires, and DE time on a track. You could buy a high-performance driving class and get more for your money. Seriously, there is really nothing short of a massive roll of cash that will make any difference in the performance of a Porsche normally aspirated engine. As others have pointed out, a diet has some merits, but there is only so far you can go with that. Porsche does a good job with wringing out the most from their engines out of the box. Adding 20 to 30 hp to an engine really only gives you bragging rights at the next water hole. If you were honest to yourself you wouldn't really notice much of a difference at all. If you want a significant improvement, sell and buy a Turbo. At least you now have a pathway to some serious upgrades. Lastly, any money you sink into your car is pretty much money burned. No one will really pay you extra for your car when it's time to sell, so the improvements are a poor investment.

Anyone have the #'s on the stock exhaust vs Fabspeed system? I'm consider a muffler change purely for weight savings and hopefully a little more growl.

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Let's be honest with ourselves here, just the act of buying a 996 is a poor investment. RE: Fabspeed vs. stock, if I recall correctly my Fabspeed cans were a good 25 pounds lighter than the factory mufflers.

people invoke the word 'investing' way to much on this car forum. "if I was to invest in a muffler...." That said, I've spent time and $$ on improving the induction and exhaust sounds, with good results. Reg size IPD plenum, fisters, headers & resonator cap have my car giving a fun sound. The car really demands that you appreciate it for what it is not - and it is not a drag racer. It's a fun and engaging canyon/gt/a-x/HPDE car.

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That's a good diet!

I had the K&N CAI kit in my hands, ready to install it after being very happy with the improvement in sound resulting from the CAI kit I installed (in about 24 minutes with no issues at all) in my Jeep Grand Cherokee Overland. However, when I saw the Direction called for drilling... I put it all back in the box and sent it back to Mr K&N. I ended up just going for K&N air filters on the 996 and the GT3. I'd spend a big chunk of OP's $2k on a really spiffy race suit and shoes so I looked at least 45hp faster.

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AGM battery??

Nitrous https://www.americanmuscle.com/zex-n...8EwA&gclsrc=ds

If you want a great exhaust cheap, buy two magnaflow 14158 and pay a custom muffler shop to pipe them in for you. Generally you'll spend about $500 all in. Shaves a ton of weight and sounds amazing. Not for the feint of heart as it's all I run on my race cars. And don't ask me if it drones because it's too loud to tell.

WHAT??

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Googles your friend. Put an Odyssey in my old air-cooled think it was half the weight of the Interstate that came out.

Here's another cool weight saver is lithium iron phosphate batteries. I can't find the battery tender version I've been buying but here is the WalMart equivalent. I run 1 but Blue Chip runs 2 in parallel. Something about AC in his track car but I can't remember for sure. LiFePO4-12V-24-35ah-Battery-for-RV

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2 in parallel. 2 in series would produce a 24v system.

Whoops. Yes, parallel.

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Maybe my question was too short, but while the interesting Battery University attachment has a lot to say about AGM, I'm still wondering why AGM and not Lithium Ion?

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Correct - I run 2 in parallel - total is 7#. Because my car does occasionally see some street use as well as some longer track weekends - I really didn't want to worry about battery life. This works perfect...

Hello Porsche Fam., Update. I believe I am looking for one more piece and that would be the IPD Plenum. Next I am going to finished up my suspension components. Coil overs, New Engine mounts, tranny inserts, power flex bushings and all the old worn out rubber bushings. ​​​​​​ adjusted list: Top Gear 200 Cell Catalytic crossover pipes. Cost $531 HP: 12 to 15 Claim Wanting these over the X-Pipe design so I can keep low end torque.=Will be purchasing within 1-2 weeks. Purchased today. $624.00 Shipped to my doorstep. Off shore brand headers. Cost $200 HP: 5-7 Claim =Not going to buy headers, but our Rennlist friend Strathconaman posted x51 headers(pics below). Got me thinking about these. vs. stock 996 headers. Air Intake ( K&N Cold air system or EVOMS) Cost $500 HP: 6-10 Claim =Not going with this. Going with 997 3.6 or 3.8 OEM airbox for aesthetics. Using the OEM paper filter as well.=Purchased the 997 3.8L OEM Airbox and going with OEM paper filter. IPD Plenum Cost $790 HP: 24 Website Claim=still searching. GT3 82MM Throttle Body Cost $200 HP: unknown =Already purchased($35 bucks shipped). Looking for IPD Plenum to complete install. Under Drive Belt Pulley Cost $ UKN HP: unknown =changed my mind. Not purchasing. Thank you, Vincent

I think you've made the right choices so far.

Skip the IPD plenum - it makes nice intake noises but time after time people have found that it doesn't do anything for power. Purely anecdotal, I know, but look around and you'll find the same info. I had one on my 2000 (the IPD comp plenum and GT3 throttle body) for a while and it sounded awesome, but I eventually removed it. It is more show than go. The smaller pulley will give you more usable power to the wheels. Best bang for the $$ on your list and you decided to skip it...

I used these Mini Cats with my 200 Cell Catalytic crossover pipes and get no CELs

+1 on skipping the plenum

Think about putting that money into more maintenance. Like cooling flush, shifter bushings, etc. This is my dyno sheet after spending 5 times your projected budget and video of 3 pulls Read the bottom signature tag to see the modifications done. Just my $.02, https://www.youtube.com/watch?v=BtWGXExfGZE&t=1s

"This is my dyno sheet after spending 5 times your projected budget and video of 3 pulls Read the bottom signature tag to see the modifications done." Wow, this is very appreciated by all who have similar questions (including me!): Just a quick follow up question. For the Evoms Stage IV, did you have a before and after dyno pull? Did you feel a major change in acceleration? Thanks!

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No dyno before modifications The dyno sheet produced in the video is a very conservative report, according to tuners (tuners did not do dyno, 2000 miles away), The local shop did not have cooling fans positioned properly, and the rear tire placement on the roller was not optimal, Add the dyno was cold, and had not been used in over two weeks, thus all of these items contributing to low PEAK readings. The part that stands out on the dyno sheets, is the duration of near max torque, look at how wide the torque band is. I point this out, because I went with a 200 cell X pipe and a Comp IPD/GT3 Throttle Body, which this thread has discussed, all of which will hurt low end torque, without a ECU tune. When the tune compensates with more fuel and more ignition timing coming in faster, you don't have the expected drop, as you would without a tune. As far as revs, nothing has more of an effect on how fast you climb rpms as the LWFW and underdrive pulley working in tandem. I have had 4 PCA driving instructors behind the wheel of the car, all 4 said the same thing, without any input from me, "WOW, this thing really revs fast" Low end inertia (torque) to the wheels is loss due to LWFW, no doubt, big difference when utilizing the 5000 rpm launch control and drop the hammer to 12.5" wide rear tires. With the standard dual mass flywheel, the car would ignite the tires, with the LWFW, it can barely turn them over, but once under motion, the acceleration is much faster with LWFW. Hope this answers your question.

Yes, thanks that answers my questions. I also have a remote tune, and wish I would have done before and after dyno runs. I sincerely doubt I got extra horsepower, but I did seem to get a more linear throttle and smooth response. I am happy with the results, but no way to really tell if anything meaningful was done.

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The results shown are hp and torque at the wheels, and not estimated engine ouputs, correct? And if so, any idea how much engine hp and torque this corresponds to? The torque band indeed looks good! Not just down low, but also above 7000. My previous (non-P) car had lots of power at high revs and reved very quickly, but I'd still say it had weak throttle response, because while it would rev when in neutral, when it had to pull the car, pushing the throttle didn't result in the same immediate lunge forward as with my 996. Can you let us know how your mods affected this (particularly the X-pipe and the tune, if you did not make all the changes at once)? Thanks! P.S. Nice looking car, by the way! If I were to repaint mine (near the bottom of my possible mod list, but it's there), Orient Red would be on my short list.

Since last visiting this thread, I remembered one theme that featured early on. It sounded like while it is very hard to really improve the engine, improving the suspension is easy. Well, making the suspension faster is easy. Making it better … . I don’t mean to highjack the thread, but it is a popular one, and some readers might get the wrong impression. There are lots of things you can do with the suspension to make the car faster on a dry track. Maybe some that make it faster on a wet track too. Doing any of that without having an adverse effect on comfort is hard. Yes, suspension technology has improved. But as (at least) one journalist in a mainstream car magazine has said, “wherever you drive, you get the feeling Porsche’s suspension engineers have been there first”. Other car manufacturers have big teams of suspension engineers trying to beat that and almost without exception, they fail. And if you invest in better damper technology for which the springs, valving, and stroke were not very well chosen, probably you will too. There may be exceptions. It would be great if there are. And while I don’t know the Feal dampers mentioned above, I had a look at their site after reading about them here and it’s certainly encouraging that, if I recall correctly, they choose the springs, valving, and stroke based on (again, if I recall correctly), the weight of your car, the weight of your wheels, and how you want to drive the car – very different from the norm. Also a possible exception to what I said about comfort (though not necessarily about making a car better), KW makes a coilover series that is specifically designed to make sports cars more comfortable. (No idea if they offer it for 996s.) In any case, I'd suggest that anyone considering "investing" in their suspension who cares at all about comfort and handling on streets that are not race track smooth do their homework very carefully before pulling the trigger on "easy" suspension improvements.

(On the other hand, you can get much more speed, handling, wet safety, and maybe even comfort from tires. Or at least you could, if Michelin were to offer their excellent PS4 or PS4S in 996 sizes. (Or if someone else offered their latest generation tire, even if not as good as the PS4s.) Why don't Michelin? Making too much money selling overpriced N rated PS2s and excellent but overly focused Cup 2s? Boycot Michelin until they see the light! I believe the N rated P Zero Rosso is the better choice anyway, and I just bought a set. I know they don't get much love on this forum, but back in the day, Porsche's official tire info showed them as being much better in the wet than the PS2s (the reason the Pirellis are N4). And about 2 years ago, Pirelli changed the compound with Porsche's blessing to give them much better wet grip than they had then. (I inquired with Michelin whether they had done the same with the N rated PS2, and they said no.) At the same time, Pirelli was careful not to significantly change dry grip or handling balance. And they do handle. They were the lauch tire for superbly handling C4S. And in the past few years, Evo wrote several times that they preferred them for 996s.)

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You make some good points After investing in engine and suspension and safety modifications. I think the suspension should be first on the list, for most DD cars, if you are hell bent on modifications. I did not go with coilovers. I went with Techart / Bilsten. It lowered the car to just what I wanted. The handing, I just can't say enough. The cars is stable and predictable on the street and on the track. I personally have not done over 135 mph, that was down the main straight at NJMP Lightning, downshifting and braking going into and coming out of turn 1 was as smooth as silk. Generally 127-130 on back straight at WGI, before hard braking and going thru the Bus Stop. I have been a passenger in my car, when a driving instructor (20 years @WGI) did a half dozen laps at WGI, claiming he was only driving 8/10. I have done a couple hundred laps there. I am in yellow run group with PCA, so it was thrilling to have a ride like that. Not only were his laps, more than 20 seconds faster than my personal best, but had me hanging on for dear life. I never had thought my 996 could be that fast and handle in turns like it did. I am years away from that level of skill, when he told me the suspension works great and the set-up was right on, it made me glad I invested in it. The reason I say this, is that many of us will never reach the potential of what a 996 is capable of, for sure not me.

Hello Porsche Fam., Thank you for all the feedback. I am not going to move forward with the IPD Plenum. I am pretty much done right now with the modifications. The Top Gear 200 cell cat just arrived at my doorstep this afternoon. Not looking forward to gearing underneath the car yet. My IMS, Clutch Kit and RMS items are in transit. I will begin the remaining suspension component purchasing next week ish. I am willing to give up a bit of comfort for a funner experience in the handling aspect of the vehicle, not going to corner at 90mph or anything like that. I have been driving the vehicle before mods, I run out of road at 5,500 RPM and I am already at 70-80 Mph merging out from the interstate loop. It gets a bit scary, I let off the gas. This is leading me closer to wanting to track but that will take more mods, more money. I might find/search for a solid center core high end under drive pulley, recommendations are appreciated. Lightening the car will be my next free mod when all this is complete, I don't need back seats. The true 996TT hollow spoke wheels are ordered, I currently have the heavier Solid spoke Turbo Twist for C4S. Going with a 997 S Shifter to tighten up the throw and make it that much enjoyable. Going to give my current 996 shifter to my buyer who purchased my old Boxster S. Thank you all, be back.

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It pulls really smooth through the entire rpm range, here is a ride along for you. The shifts are a little below redline. You can hear in video and watch the tach to see the 5k launch work, then see how bag it bogs when you drop the clutch due to the LWFW. (No laughing at my reaction time) You Tube

Have you considered an LSD/TBD? it would certainly make for a funner experience in the handling aspect of the vehicle

Just a quick inspect. Function First Orange tranny inserts. Softest version. Rusted nuts and bolts on the catalytic clamps Passenger side installed. Top Gear 200 Cell cats. Thank you for the new nuts, bolts and gasket. Top Gear 200 Cell cats. Looks good. Front picture of semi solids. In the ad, the poly piece is blue. It is all black here. Hopefully they did not send me the full track version. Rusted nuts and bolts. Used for measuring to source M8 replacements. Driver side semi solid motor mount installed. Function First Tranny inserts and semi solid motor mounts. Rusted nuts and bolts. Used for measuring to source M8 replacements. TT Hollow spokes. TT Hollow spokes arrived. Just cleaned them up. Sumitomo HTR ZIII Driver side muffler and tips. In bad shape. Tires are bald and showing the wire. 997 3.8 factory airbox installed. Plug and Play. Picture of factory motor mounts after removal. Factory 997 3.8 Airbox arrived. Just getting ready for some work. My PSE Vacuum Actuator passenger side. Looks good. Top Gear 200 Cell Cats delivered less than 4 days. My PSE Vacuum Actuator is toast. Driver side. **Update with Pictures** Hello Porsche Fam., Sorry for the long delay. Been working on the removal of Cats this weekend, installing semi solid motor mounts, attempting to remove PSE mufflers, installed factory 997 3.8 OEM airbox and a lot of rusty broken nuts and bolts. Here are a few pics. There is a lot of rusted bolt and nuts that I had to break off. I could not for the life of me remove the o2 sensors, going to bring it up to the muffler shop and have them attempt it. Sourced new M8 anti-corrosive bolts, washers and nuts for the muffler clamps etc. My Factory Twin Turbo Hollow spokes came in. Debating if I should powercoat them gloss back, gunmetal seal gray or keep them the same. My tires were in bad shape, bald and wires are showing. Looks like I have some negative camber.

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Really amazing stuff! Hey I did not see the Stage IV tune with launch control on the Evoms website. Was it a custom tune? Did you have it done at a local shop? Thanks!

OP I did the same stuff as you; with inserts, semi-solids and TG cats/mild sport. I think you’ll enjoy a nice sound and small improvement in performance. The NVH is just right for me. I don’t think OK has any smog inspection, but I did find I needed O2 extenders for the cats to post “ready” status with the TG cats. I’m also considering the 3.8 airbox. How was that install and what’s your new opinion on that mod?

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Sorry NYoutftr, I see you answered the local shop question above. Just interested in the Stage IV with launch control info.

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Above all else I'd be worried about the soot in the driver's side tailpipe. Thats a huge red flag that you've got failing injectors on bank 2, and this is usually a precursor to cylinder scoring. Approach with care. Bank 2 is certainly over- enriched~

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I just ran out and checked mine, no soot. I cleaned both tailpipes off so I can keep a closer eye on them. I bore scoped my engine when I installed the 2qt deep sump last weekend. It looked great. Manometer looked good last time I checked the AOS.(5K miles ago) I don't have to worry about the IMS Bearing, I have The IMS Solution. Any other things to keep an eye on?