Originally Posted by jgporsche

I gained 10.9HP and 11TQ at the wheels with a Speedforce Racing exhaust. The exhaust was from the headers back. It was a full 2.5" stainless steel system. It has a high flow cat, bullet muffler and 4" tip. My opinion about exhausts on these cars, is that you DO need some kind of restriction in the system, too much free exhaust will inder your performance. This is why I have both the muffler and high flow cat.

Originally Posted by TheRealLefty

This a familiar, but always interesting discussion. Short of an old school bullet proof $30K-40K full race build with custom internals and massive upper end redesign (read JME SCCA motor) significant NA horsepower gains are hard to come by and very expensive when measured by "dollars per pony."

Lacking the proven combination of engine management and WG mods that can instantly ramp up a healthy 2.5 Turbo by 50-100 HP, gains with NA's are measured in 2-3 HP improvements.

I have a JME Stage One cam, cone filter, throttle cam, fresh Turbo valve springs, adjustable FPR and a custom low restriction header-back exhaust with only a Flowmaster 40 muffler and I don't think I've gained 10 HP over stock, if that.

FWIW, scuttlebutt suggests that a Jere Stahl header is just about the only NA bolt-on that makes a big difference, but like the JME cam it's a $700+ hit for a couple of ponies. Word is that the real deal killer in all of this is not intake or exhaust breathing but rather the head itself. The valves are big, they move a long distance and there's a lot of flow disturbance in their wake and therein lies the rub, apparently.

As advised above, best advice for NA performance is to take out weight, keep up your momentum and enjoy one of the best handling cars ever produced.

Originally Posted by upcruiser

exhaust- Are there any header setups that you guys have good experience with?

Originally Posted by knfeparty

The 2.7 is nothing to write home about. Doesn't it, according to Clark's documentation, only have 4 more hp and identical torque?

Originally Posted by jgporsche

I gained 10.9HP and 11TQ at the wheels with a Speedforce Racing exhaust. The exhaust was from the headers back. It was a full 2.5" stainless steel system. It has a high flow cat, bullet muffler and 4" tip. My opinion about exhausts on these cars, is that you DO need some kind of restriction in the system, too much free exhaust will inder your performance. This is why I have both the muffler and high flow cat.

Originally Posted by M758

Headers.... Stahl headers are the best. Cost is about $650 for the set. Then run with test pipe (no cat). Gain is maybe 5-8 hp. Then get a Borla XR-1 muffler.

Now you will also want to have chip custom tuned for the exhaust. Cost will be quite high, but you might be able to break 140 at the wheels if you do all this on fresh engine with top end rebuild.

This is from experince in the 944 spec world. By contrast stock headers & chip will get you 134-135 whp with fresh stock head. I figure 131-133 with stock chip and stock headers.


Intake the best is stock if you stay with Barn door AFM. You could also add in an adjustable Fuel Pressure regulator and maybe see north fo 140 at the wheels. However you will need to dyno time and lots of it to see the gains. Just bolting the parts on you won't see much, but bolt them on then tune the crap out if it maybe 145 rwhp. I'd figure about 1.5 to 2k for parts and dyno time.


BTW... this why 944 spec just went to stock headers only and stock chips. We always had stock Fuel pressure regulators, stock AFM's, and stock cams.

Originally Posted by upcruiser

Thanks Joe. Do you have a link to Spec 944 specs? Not that I'm setting up my car for it right now, but would like to keep any upgrades I do inline with what can be run in it. I dream of being able to run in that series, but it would be a ways down the road still. This way I avoid doing anything expensive that might be throw away money down the road. Just trying to keep my options open.