r4_rick

Hello everyone
What do you get the most benefit from in changing either the manifolds or the "end boxes", there is a german outfit selling Stainless manifolds on the bay £580 claiming 8-10% power increase , sounds good to me !
a) power
b) sound
c) weight
Budget, at the moment, doesnt stretch to the full works !
Appreciate views from those of you who've upgraded the exhaust, seems a shame to have a 911 without the full sound sensation !
Rick

Jacks911

10% of 300 HP would be 30 right? May sound good - but all the post I have seen on Rennlist would seem to say it would take a lot more money to get that kind of improvement in a NA M96 motor - and far more that just one part of the exhaust system.
Two articles, replies to letters, in Excellence have stated that there are very few proven full exhaust systems on the market that they have tested and seen a "noticeable" improvement in power. I happen to have one of those - a full TechArt Header System. But even that @ $3500 is only claimed to get 28 HP - With a DME Remap and intake air-cleaner filter mod.
HP improvements on most E-Bay ads are like "Snake-Oil" sales at the Carnival - but you can believe it and spend your money. I suggest you talk to a good Indy before you run your charge card.

Imo000

As a rule of thumb, always take HALF the HP that the manufacturer of an aftrrmarket claims. In this case, 4%. 12hp at the crank, on a 300hp engine will not be noticable. Buy it for the sound.

white out

Yeah, it's probably closer to 10-15hp gain.

pmkazz

Well, be very careful because most times you will actually lose power from some of these aftermarket exhaust componets, especially low-end. Most of the time, the power curve just gets moved around, meaning you may get a little more power at the high RPM range but you will lose low-end torque. I know of two companies that actually design, build and "performance test" their exhaust system components specifically for performance. These companies are Cargraphic and AWE. There may be others that I am unaware of.

steepsnow

I have some related questions as I have a damaged "Cat." I am considering Cargraphic and Fabspeed replacements with 200 cell Cats.

I also have OEM, PSE with a rattle on one side. Thus, I have two options: 1) repair the PSE by having an exhaust shop open and repair loose parts in the PSE muffler or 2) replace the mufflers. Would new mufflers combined with their matching cats from the same Mfg improve performance or just the "sound" as compared to the repairing the PSE mufflers?

Lastly, what about the headers? Are the Stock headers good enough or would it make sense to replace them along with the Cats? ...and possibly the mufflers?

Basically, the question comes do whether or not all three parts together are required to reap any real benefits as compared to just changing the cats.

Also does it require other parts or ECU programming to truly get a performance benefit of any or all of these exhaust mods- as compared to just some volume and tone changes?

Thanks!

alpine003

This. And more importantly for a street car, I would rather have more improvement "under the curve" rather than all out peak hp.

ivangene

dyno the car before and after - I bet you see little to no change - if no one demands proof these claims get wildly exaggerated over time

pmkazz

Stock exhaust manifolds are good enough. Headers will not add much if anything to performance and---you run the risk of snapping exhaust manifold bolts, especially on an older car. I would replace the Cats (Cargraphic or AWE) and go with the 200 cell. As far as mufflers---do you want to retain the PSE?? If so get them repaired. Aftermarket mufflers will not really increase performance but will sound better. Best muffler modication--IMHO, is to gut the stock mufflers and add 200 cell cats. Great sound and performance enhancement..

Throttle

Per Alpine003, "And more importantly for a street car, I would rather have more improvement "under the curve" rather than all out peak hp."

I was all gung-ho to change to the Afterhours Sport primarily for the sound (not too loud, but a nice growl when you get on it) and because it did not appear to negatively effect low end rpm performance (see dynocharts on their website). But I discussed changing the stock exhaust with both my Indy mechanic (Porsche certified) and the a friend who has raced cars and both strongly recommended against it given the number of people who they have seen change a 911 exhaust only to regret it. I'm still tempted given the "wife friendly" design of the Afterhours Sport, but haven't pulled the trigger yet. BTW, I have a Cabriolet, so definitely am sensitive to too loud.

pmkazz

One of the best muffler modifications I have used on the 996 is to have the stock mufflers cut in half, remove the enternals and re-weld the mufflers back together. This makes them extremely light, gives a great sound (not loud supprisingly) and good performance. Hergesheimer MotorSports in Lake Forest, CA used to do this modification, but I would think it could be done by others with the right tools (welder, grinders, etc.). We are currently running this setup with AWE 200 cell cats on my friends track car and it works very very well. And again, it is not loud and there is no drone. Has a great sound!

LC MotorSports

As we talked about today.... The stock Headers are the best (unless you really plan on going racing... then you would see the most benefits from a remap to maximize the system), upgrade to set of 200 cell cats and go with the Super Sound version. The system will work across the full RPM range without low end torque loss and no remapping needed to see about 7 to 10 hp gain.
Drop me an email and I can work up the cost for you.

alpine003

PmKazz I know you talked about the gutted mufflers before but just wanted clarification that there is no drone even with the 200 cell cats and the mufflers were FULLY gutted with no baffles or insulation whatsoever? TIA

pmkazz

Correct. Completely gutted. No drone... The best way I can describe it is, it sounds very Ferrari-ish.. The mufflers by themselves sound incredible, but much better with the 200 cell cats. And----There was NO low-end loss of torque with this setup and we have experimented with a a number of combinations. PM me if you want to discuss more...

white out

A tune would net the most from your mods.