Question on X51

I have a 2002 C4S with PSE and love the way it sounds. I'm thinking about the X51 power kit. Previous threads have discussed whether the car feels faster, but my questions are: 1) Does it change the sound of the car? 2) Does it change the "personality" of the car? Would appreciate input as $13k for the modest speed increase alone will not do it for me.

are you going to track the car or is it mainly for street use....?

For the money spent its not worth it. Sure I would do it if the engine has to be taken apart, but the cost of the parts and the labor for a perfectly good running engine is not worth it. You'll be better off selling the car and finding a turbo instead. I'm also not that big of a fan of S/C the car as I just don't think adding boost to a 11:1 compression engine is the wise thing to do. I know lots of people have good results from it, but I'm just not a believer.

I saw an 03 with the X51 package for $63K. If you consider that a clean 03 will be in the mid to high 50's then the X51 after the fact package really doesn't look good. You could chip the car and add an exhaust for under $2000. Get maybe half the X51 power and tune the exhaust to your own ear. Even with the PSE you'd still be at around $2600. Crap, I'm talking myself into another mod.

The X-51 kit has been discussed a great deal. It's very expensive and yields a modest increase in power. The car sounds the same. I've never ridden in a stock 996 so I can't tell you how my car feels compared to a stock 996. I can tell you that the engine is very flexible and pulls very hard all the way to the red line. However, I don't think that I would spend the money to put the kit on a standard 996. Options? A chip and exhaust will not yield any appreciable power gains in a 02 and later car. I would look to a supercharger. You get very impressive gains at a lower price point and they have so far been reliable.

If the X51 extended my engine warranty, I would do it after my warranty ran out. Otherwise, just sell the car and buy a used Turbo.

There is an engine power kit offered by Alegra Motorsports that *does* give noticeable gains... much more so than the X51... my friend blew the doors off every stock 996 this weekend at mosport here in Toronto...

The X-51 is a great option if someone else pays for it like the first owner. I would had a super charger 10 X overs befor i spent the money on the X-51.

I follow the opinions of the rest here in advising against buying the X51 package and upgrading. For the money a supercharger is a much better bang for the buck. If you were looking at changing cars, it would be a different story. An 04' 40th An with the X51 would be a nice option. I have driving a couple X51 cars and many 996 3.6's. The X51 is different in that it pulls more only at the top or the rev range and doesn't have a rush of torque at about 3000 rpms the regular 3.6l has. It is not a significant difference, probably not more that just variances between cars. In fact, this upgrade on a C4S will only make your car equal in power to weight with a standard engine Carrera 2. For sound, there is no difference between the two. I am very skeptical of the claims of 10 hp from an exhaust and 20 hp from a chip and intake. I have been monitoring these boards for a while an no one ever posts independent dynos of the results. It is always by seat of the pants. Seat of the pants once told a supercharger upgrade was making more power, but it was the dyno that told me I was still making 20 hp low due to a boost leak.

I've driven a 40th anny with x51 vs. my 3.4 with engine mods. Honestly, the difference is minimal. I was expecting a more dramatic change, but drivng around town, it felt exactly like my car. The only difference is in the higher RPMs. Not to knock x51, but if I had the money it would go into a superchager

My C4S is a weekender which I use mainly on the road with plans for occasional track use. I'm surprised to hear that the X51 power kit didn't alter the sound as I recall Porsche stating that the X51 especially with the PSE results in a more aggressive sound.

It's the PSE that changes the sound, not the x-51

Sooo, would this one be an ok deal then?? http://cgi.ebay.com/ebaymotors/Porsc...QQcmdZViewItem

I guess I have a little different view of the X51. I think it's a great package. One of the problems is that most people have only driven one in a 40th Anv car. The 40th is a great car and a great bargain but, because of all it's options, is a pretty heavy 996. If more people had a chance to drive similar 996s with and without the X51 I think their feelings would be different. Now, should you put one in a C4S. I know I'm going to **** some people off and I apologize ahead of time but a C4S is not the car to make go fast. Pretty, yep. Great commuter car, yep. Great GT car, yep. Great sports car, maybe not. It's way too heavy. Personally I'd enjoy the car the way it is or, as suggested, trade up to a turbo. Still heavy but with more power. If at some point you want a very fast 996 think in terms of light weight first and extra power second. Just my 2 cents worth. I could be wrong. Jim

X-51 car sounds different when your in the cockpit... you can hear the high pitch wine of the cams above 5000 rpm... something a non-X51 car doesn't produce.... outside they sound the same though... it's a nice sound inside the car that's for sure....

I have driven 2 Jahre (40th An) editions. The X51 does change the character of the car. That noticeable punch in the back of torque at 2500-3000 rpms will be gone. It does rev smoothly, you just lose that quick ramp-up of low end torque. This is the trade off. You have to give up some of the low end everywhere below 4500 rpms and gain some that isn't noticeable until above 6000 rpms. Most of the ECU tuners readjust the limit to 7500 rpms on these cars to get a better benefit from the higher powerband. Keep in mind that since you have a C4S that your car is 276 lbs heavier than a regular carrera. Going the X51 route only evens the power to weight with a regular Carrera. This should give you an idea of what the improvement will be. It is quite expensive for these gains. You will find better options in selling your C4S and looking for either a Turbo, Jahre or a GT3 instead. Now only would you get the extra power, but also a better suspension and significantly less weight (JAhre and GT3) at the same time. Providing you have reasonable mileage on your car then the trade of your car + $13K should be able to get you in a Jahre or an early 996 Turbo. The X51 doesn't change the sound of the exhaust. You need to get a different exhaust for that. Just keep in mind the the Porsche PSE does not increase power, only sound. If you are looking for performance gains then you are best off aftermarket with something like a Fabspeed. There is a comment about hearing the cams. From have driven 2 X51's, neither had any additional noise. If you are getting cam noise, it is probably a valvetrain problem. Neither car sounded any different from a regular Carrera.

Here's a clip of an X51. I'm not sure if it's the cams but it does sound different than my other 996. http://www.youtube.com/watch?v=omFPQenVdbQ

I'd like to contribute to the discussion of the X51 and share my experience. My 2002 C2 Coupe, which I ordered from the factory with sports seats, sport design wheels, sports suspension, PSM, etc., has had the X51 kit for almost 3 years. When I placed my order I wanted a well appointed, but light road car that I could take to the track occasionally. Unfortunately, back in 2002 the 320hp engine was the only choice. The X51 option didn't became available until 2003. Here is my story... after only 1,400 road miles I found the US sport suspension too soft, so I installed the ROW-M030. After my first few trips to the track I felt underpowered. So shortly after 4,000 miles I had my dealer install the X51, and a short-shifter kit. Now I couldn't get the car slowed down. I was carrying too much speed down the straight and had to brake earlier and earlier. So I had the Brembo Gran Tourismo kit installed at 7,000 miles. Now I had power and brakes, but the suspension was too soft, again. At 7,800 miles I installed H&R sway bars and set the rear bar to stiff. The car ran flatter and was neutral, but still too soft. So just after 12,000 miles my dealer installed the Porsche X74 suspension (from Carnewal). Finally... (after 15,000 miles) I have a balanced package. The X51, X74, and Brembos are the perfect setup for a C2 Coupe if you want a road & track car with Porsche parts (Brembo is the Porsche brake manufacturer). By the way, I always run Michelin Sport Cups at the track, and can now stay up with most of the newer cars in my DE Day advanced/instructor group. The sound of the X51 at high revs IS different. Not terribly louder, but it has a fuller exhaust note not unlike the GT3s. But you won't notice any difference on the street. And the advertised 25hp increase? Believe me, it's more than that at speed. For anyone thinking about adding the X51 kit, or the X74 or Brembo brakes, my advice is to look at what happened to me... and look at the whole package. I hope this info helps. TNG