Yet another PSE style exhaust mod

The 996 is an awesome machine, but many of us long to have a more aggressive exhaust note while at the same time keeping the tone reasonable. Last year for a few track days I removed the mufflers and fabricated some slash-cut 3" polished tips. The sound going down the main straight at NHIS was heaven, but it was barely streetable and my wife refused to ride in the car. So I wanted to do a modification that would sound similar to the PSE - either mkI or mkII. I decided to go with the mkI style where a small bypass pipe is cut in, between the inlet and outlet of the muffler. Searches on the forum will reveal a lot of detail on the PSEs and other similar mods for comparison. I went with a larger and more direct design for the bypass using 1-1/4" 304 SS U-bend tube obtained from Classic Tube below: Classic Tube [phone removed] http://classictube.com/ Item #65-180-125-20 Part: 16 Gage - .065" Wall Description: 180� "U" Bend 2" Radius Legs 6" x 6" Make/Type: 304 Stainless Steel Model/Size: 1-1/4" The U-bend tube was about $30 and cutting it in half produces stock of the appropriate size for each muffler. After laying out the best location to minimize clearance issues, the two tightest being the header-cat flange and the chassis, I used a hole saw with a 1/4" center guide to cut the openings. After a bit of fitting to shape the openings and the tube ends, I welded in place. I'm pleased with the end result, both from the standpoint of the modification and the resulting sound. The exhaust really comes alive with a nice rumble and a bit of a bark when tapping the throttle. Being in the northeast, I have not had the opportunity to bring it out on the road yet, but hope to in the next few weeks. I have attached before and after sound clips and pictures of the steps in the fabrication. Hopefully the quality of both will be adequate as I only used my treo to record the clips and photos. -Wayne

Wayne - Good job! It sounds great! Very similar in sound to the PSE MK II on 3.6L mufflers. It is certainly better sounding than the PSE MKII on 3.4L mufflers.

Sounds nice! Did you use the 3.4 or 3.6 cans?

I used the original 3.4 mufflers on my 2000 C2. I think the increased diameter and more direct route (as compared to the mkI PSE style) helps make the tone a bit more throaty. It is also relatively easy to do once the design was determined. Being able to purchase the mandrel bent tubing also helps simplify the fab. -Wayne

That sounds amazing! How does the car sound when it is not accellerating? I am very tempted to do the mod but I want it to remain a daily driver yet sound throaty when I accel.

How would you describe the sound at normal highway speeds (70~80 mph) following this mod; any significant and/or objectionable resonance affects?

This has come a long way from the original design.

I love the "On/Off Switch" on the original design!

At least they sealed it tight with teflon tape between joints!

WOW!...Ghetto all righty...

Please tell me that's a PS job!

This mod is very akin to what the C5 Vettes are doing. It was the best sounding mod at a fraction of the price of aftermarket systems. And you have done a great service in recommending a place to get a hold of the by-pass tubes. You could make a business out of pre-cutting them and selling them. Several vendors have on the Vette side. And another business can be buying up take-off cans and modding them and selling them with a core exchange. Just in case, how much would you charge to apply the mod to my original cans sitting in the attic?

Can you put out a sound bite of what the car sounds like INSIDE the car during normal driving and also one while driving the car all out? I am still not sure if this is a mod that I can live with during every day driving.

ToolPants, that original dsign certainly set the bar in creative use of plumbing supplies. Melchior, unfortunately I have not had the car out to try it because of the salt covered roads around here. I will be sure to post the results and sound bite when I do. I can't wait to hear it under load as I have high expectations based on the sound so far in the shop. PorschePRH, the fabrication is fairly simple using the mandrel bent tubing. I would expect that a local muffler shop could do the job if supplied with the pictures and the tubing. I just don't have the time to go into production. To busy dreaming up other mods! -Wayne

It finally warmed up and the roads were clear enough to bring her out for a test drive of the PSE mod described above. All I can say is it rocks! The sound is perfect -imho- with just the right tone and sound level. I did not detect any drone or vibrations. It is exactly as I hoped it would turn out as the mod accentuates the sound when you are accelerating, but much less so when at constant speed. I wish I had thought to grab some sound clips while driving before the mod for comparison, but ... I have attached three additional sound clips; one with windows down and stationary, one windows down and driving, and one windows up and driving. The windows down recordings are with my treo held up to the driver's side window and for the windows up recording I put the treo on the rear seat back folded down. I hope this is helpful to those considering doing the mod - a flat6 symphony awaits. -Wayne

Wayne - that is a good comparison between the three different clips. I have to say that those clips are very similar sounding to the 3.6L mufflers modded with the MK II PSE mod (currently on my car). I think you have demonstrated that the MK I PSE mod (or your variant) is better sounding than the MK II PSE mod option for the guys with 3.4L mufflers. Well done!

Sounds very similar to my 3.6L engine w/ 3.6L cat w/ MKII. Good job.

I performed this mod last weekend following closely the instructions provided in this post. It took a couple of hours plus time to get the welding done. FYI - Be sure to allow for the extra effort of cutting and trimming the SS tubing; it will quickly dull a typical hacksaw blade. I used my bench grinder and pneumatic die grinder to produce a close fit for tig welding. After installation (Now I�m sorry I didn�t record stock levels, too) I was able to borrow a sound level meter and recorded the values shown below. These are averages of two constant-speed runs, one in each direction with the windows up and radio off on my 2000 C4 coupe 6sp daily driver. I can confirm previous post about no resonance or drone at cruse. Idle has a nice sound, too. Level is a little louder than I wanted when at mid-throttle acceleration, and while low in tone it also has a high frequency component I attribute to the small diameter SS tube dumping in so close to the end of the exhaust path. Overall the engine seems really crisp and pulls more easily at low RPM in higher gears. I suspect, but did not measure, a significant reduction in exhaust backpressure. Speed - �A� weighted sound level 60 MPH - 66 db 70 MPH - 69 db 80 MPH - 71 db

that kicks a$$... thanks wyane.... i think this is the next mod for me.... anyone in Socal willing to help out a fellow pcar brother...?

I'm happy to hear that others like this mod as much as I have. I think this is a good approach for those with the mkI 3.4 mufflers. The mkII mod may be best for the 3.6 mufflers as the flex joint at the inlet would probably be in the way of this design. I have added a few more pics of the modification in case it helps others interested in doing this project. Dscott, the db readings are helpful! I'm glad you're happy with the result. -Wayne

Anyone else done this mod recently?

Hello: following your guide I made your modification propousal in my 3.4 MK1, but I have introduce an improvement, it is an exahust valve in the middle, so my plan is to install now the PSE button in the car so I can decide on/off as the original porsche PSE system. Now my only problem is to know parts number of the button and also to know from where take vacum air conection. somebody knows?

Hmmm, this is the first I have seen of this hack. Why has this one gotten so much less press than the other pse hack?

I just got my mufflers back for my muffler shop yesterday. I had them (folks at the muffler shop) order the pipe for "Classis Tube" but when it arrived it looked way to small so I had the muffler folks use a 1 1/2 pipe and bend it and had it installed on the 'cans'. While all this was being done (I give them the mufflers around the middle of March) I've been driving around with the muffler by-pass pipes.....very loud, so I was getting kind of pushie about getting the job done. I got the mufflers installed about 2030 hours last night and just had time to start the engine so I could hear the new sound. Much better then stock and much quieter then the muffler by-pass pipes. I'll finish up this afternoon and see what it sounds like on the road. Now I have to find a home for not only the Classis Tube pipe but also the muffler by-pass pipes. Anyway ya'll can add me to the MK I or MK II, which ever this kind of 'MOD' is, better sound group! Have a great day, Patrick

This is my recent exhaust mod. Dual bypass pipes. Similar to Gembella. http://videos.pcars.us/video/64c9ccf...990000677f.htm http://videos.pcars.us/video/0941f27...9801438f37.htm

I know I am bringing this thread back form the dead..but has anyone else done this recently? Wayne (the original poster) used 1 1/4 pipe between the inlet and outlet. I am just wondering if anyone else has done this, and what are your results? Have you used the same sized piping? Will a larger diameter pipe produce more sound? And can I bring this to any muffler shop and have it done? Do they generally have this size/shape piping in stock or is it something I should order in advance? Thanks alot!

I have done the mod on the stock mufflers of my 2000 996 with the 1.5" pipe. I ordered a U-shaped piece online and for the cutting and welding I took it to a local fabricator that I found online. This was after getting very lukewarm responses from the local big chain muffler shops. The sound at anything above 1/3 open throttle is pretty aggressive, I would say close to straight pipes, and do not recommend even more blow-by via this J-pipe. Joost

wonderful. I might have to go with 1.5" then. Out of curiousity, do the local welders no have 1.5" pipes lying around? Must it be ordered online?

Just did it...3,4 can,...perfect sound ! Now it sound like a Porsche. and on highway its like there is no mod. Only in load you can ear this great Porsche sound. Thx

Joe, the sound is greatly improved isn't it? Now down to business! It is customary for Newbies to introduce themselves and post pics of their Porsche! You might want to start a new thread for the introduction and pics. Consider this next sentence your "Newbie Initiation!" Come on Newbie, post the !@#$%^&* pics! Damn, it felt good to say that again!

I am salivating to hear this. Can anyone repost the sound clips? For some reason the ones from 07 are coming up as "invalid or corrupt" when I open them. Thx.

I did the 1-1/4" mod recently and, coming from factory MkII PSE, it is not loud enough for my tastes. I would rate the 1-1/4" pipe hack about a third of the way between stock and PSE in volume. The sound is not as low in frequency as it would be with a larger pipe. Mostly a mid-range frequency volume increase. I'm glad to see jperquin tried the 1-1/2" pipe. If I were to do it again, I go at least 1-1/2" probably larger, maybe even 2". I think some guys have done the 2" direct bypass (inlet - outlet) pipe on 997 stock cans with excellent results.

The sound is greatly improved indeed ! I do DE events with PCA and I can tell you that my exhaust sound almost the same as other with sport or modified exhaust. If you want more sound at idle or no load then go bigger, otherwise I love it that way, not loud at all at part throttle, but when you floor it ...wow great sport sound. Simply I love it that way. Its a question of taste. Will post my pics soon !!!

Oh yeah, and by the way it cost me 8$ for the pipe at the scrap yard at a bottle of wine for the friend who ''tig'' it.

Curious, does this mod add any Hp?

No, it does not add any HP. Just better sound so it adds to your "enjoyment HP."

Everything that I think is going to be straight forwards winds up being anything but. I decided to go with this mod and bought a set of 3.4 cans from a fellow Rennlister. I ordered the stainless tubing from Classic Tube. I printed out all of the pictures and took them to a local muffler shop that does custom work. They didn't want to work on them because of the stainless steel, but recommended a welder in the area. I took everything to the welder and showed him the photos. When we pulled the cans out of the box, they were different than the ones in the photos. There are bellows in the place where one of the holes needs to be drilled, so this mod can't be done. He said he might be able to move the tube to another location, but then I'm not sure if it would be in the way when trying to install them. His estimate for doing the welding was $300, and I don't want to take the chance that after all of that, they won't fit. Apparently Tip cars have these bellows for some reason. Does anyone have pictures of the mod with these kinds of cans?

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Bellows? You must have a 3.6 can instead of 3.4...... you can still do this mod.

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Not necessarily, my 3.4 6spd had bellows on the mufflers.

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I dont think so.... are you the original owner? Cans with the bellows started with the 3.6. Your 99, did not come that way from the factory.

I've been told that Tip cars came from the factory with bellows on the exhaust. My 2000 C2 Tip has them as does the set I bought from another Rennlister with a similar car.

Your voice is amazing.Bravo. But ı want to ask question. I listen your clips. 'After ' clip voice is some like too much voice or maybe your recording tape. but my question. for example fister d 996 sport mufflers vs your sport mufflers. the voice is same or your voice is little much. ıf your voice is little much how can i decrease this voice little bit. do you have any other camera recording - starting the car - increasing the speed. thanks a lot. SS

Why waste the time & do a ghetto job when you can just buy fister D's for only $250? & get excellent sound!

Kardeşim. This is so hard for me. Firstly You know i live in Turkey.I cant send my mufflers back to Darin Fister. These things is so hard in Turkey. Second thing If Darin Fister will send to me my sport mufflers. I search this thing.Maybe i cant take this from Turkish Customs. Because there is some hard things. And ı cant send my mufflers back so my price is increasing. Not 200 dolar. 200 dolar + 395 dolar + ups price 200 dolar + not secure for custom. Actually I want to buy Darin Fister sure.But ı must make myself. So ı must take this questions answers.My before message.Please give me answer about this. Because this is dangerous if i make this mod to my mufflers and its very very high voice. ı am unhappy

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Evet Kardash, i wasn't directing the comment to you, i know your in Turkey & wouldn't beable to get FISTER D i was directing comment to the guy who made the thread As for the sound, yes if the sound is LOUD it will not be good, so you MUST make sure you make this mod correct, and find a good shop & welder to do it...maybe would be good idea, to buy a set of USED Porsche Muffler and do it on just incase its too loud & you dont like you just put yours back on! Here is Video Klip of FISTER D on mine, i really love it..not loud but perfect & only a bit loud when i punch the gas! http://youtu.be/itiC_wMmNKw

Okey kardeşim. Yes this is good idea. İf ı can find used porsche muffler , I will make this. Thanks for this idea. And your Pcars voice is wonderfull . Thanks

Did this PSE hack to my stock '99 cans about 6 weeks ago. Used 1.5" stainless "U" mandrel bent tubing. Worked perfectly. The car now sounds as it should have from the factory. The hack was done by Sportech here in Campbell CA. Was the first one they had done on a 996. They have been modifying stock 986, 914 and older 911mufflers for years! But my 996 was the first time they had cut and modified a stock 996 exhaust. Usually customers want brand new stuff like Factory PSE, B&B, etc installed. Showed them the pics and a couple hours later I was on my way. A very worth while mod if you like hearing your car

One of the best sound improvements other than an aftermarket system which costs considerably more.

Has anyone done the MKI and MKII mods together on a set of 3.6 cans? I have already done the MKII mod to my 3.6 cans, love the sound, but a little more noise would be nice. If it makes a difference I will most likely do it, but I don't want the hassle of lifting the car taking off the wheels and bumper cover, pulling the cans, and cracking out the tig welder if the difference wont be that noticable.

Thanks for the detailed instructions. I just completed this mod and it is awesome.

I'd like to try this mod. I think if you could add a valve to the pipe then you could turn the bypass on or off. Valve open and bypass is on for more aggressive sound and valve closed and you're back to factory sound. Then get a PSE button and hook it up to control the valves. This might be a fun project. Anyone know of any after market valves to use? Preferably vacuum actuated so that the button hookup is just controlling the vacuum valve.

Maybe something like this: https://www.ebay.com/p/?iid=322233219037

Or an electric one like this http://m.ebay.com/itm/252940943864

Old thread, but here goes: I'm about to go the Fister route myself, but I'm having trouble deciding what size I'm going to use on the bypass tubes. I know it's been a subject of debate, but I'm torn between 1 1/2" and 2" pipe diameter, and weither to get them welded like in this thread or just straight from inlet to outlet (without the half-U-bend). I'm thinking 2" might be too loud, even if some people describe it as being "mild". I do have the Carrera Power Kit, so I guess my headers give off a little more sound than the Stock ones - and I'll need to identify my cans as I have a mk1 with a retrofitted 3.6L. What are your thoughts about 1 1/2" vs 2" and "half-U bend" vs "straight" welding? --- Marius

Rolling in here as a result of finding this thread to be the most informative so I took my mufflers down to a local muffler shop that has been around a looooong time. They've never done this one but given the amount of 'salt on their shoulders' (read: they've welded a few things before), I decided to let them git after it. Here's the rub- I'm doing this mod for a 996 GT3 and there are definitely 2 'gotchyas': 1. If the weld to the 'inlet' tube of the muffler is too close to the cat/muff junction, it will interfere with the factory headers! 2. If the weld to the 'outlet' tube is too close to the muffler shell, it will interfere with the header/cat mating plates! Wally (the welder) looked at the photos in this thread and eyeballed it to a 'T'. I got extraordinarily lucky this afternoon when I hung the mufflers and you couldn't fit a gnat's eyebrow hair between the bypass pipe and the factory header outlet tube. I'm taking him a 12 pack tomorrow to keep the karma heading in the right direction :-) and this is not to mention the poor SOB sliced the end of his finger off when his hole-saw blew apart and fragged his finger. He had his entire finger wrapped in black tape when I picked up the mufflers and he told me how all the blood got on the muffler. Wally was unfazed by the event as he was still working on another car when I showed up...he was not seeking a safe space and a bubby but I digress... BTW- I went with a 1.5" bypass and you don't know how much is 'enough' until you know how much is 'too much'. I had muffler bypass pipes on for a week and while the car is not a DD, it was 'more than enough' for 70% of my driving. This mod (along with the Sprint Booster) are the two best things I believe one can do to put the right sound and throttle response into an already wonderful machine.