Rick in Colorado

I know that this subject has been discussed often, but here’s my $.02. Most of us replace our stock exhausts for any (all?) of four reasons - and - we all tend to agree that the first three are indisputable:

· Weight savings. The hidden benefit – stock components are porky and the leading replacement systems seem to use higher quality construction to boot. And weight loss not only is quasi horsepower (as recently reported 10 lbs = 1 bhp), it aids in handling/braking/fuel economy as well.

· Sound quality/volume - the reason that motivates us most. While the stock 997 sound is light-years ahead of the stock 996’s, we are all looking to duplicate the classic air-cooled visceral experience. I think that we all agree that a replacement system is a take-it-to-the-bank improvement. The only debate is PSE vs. aftermarket and, within aftermarket, which is best.

· Appearance. Another no-brainer. The stock system, especially the headers, are hideous - a clunky, embarrassingly designed, welded together mess. [which is the basis of my power viewpoint below] The area where PSE has it all over both stock and aftermarket is the true quads vs. pseudo quads tips. Do any of the aftermarket providers have the true quads design?

· Power gains - the eternal debate. I, for one, think that the “no gain” folks have a faulty argument. One look (and listen) to the stock exhaust tells me that there is a cork waiting to be unplugged. On the aftermarket headers, especially, those smooth bends have to be unlocking power over the abruptly angled, cast iron monstrosities that they replace. I’m a life-long Harley rider and the first mod that we all do (called “phase 1”) is a less restrictive intake and exhaust. And…we’re all dyno-happy – that mod is invariably good for a proven 15-20% gain. Now, I’m sure that the stock Porsche engine is more tightly wound than a V-twin (and hence, less to be gained), but it’s just basic engineering. I’d guess that instead of 15-20% that we see on an H-D, 5-10% is within the realm of reason on a 997. 5% for catback/CAI and 10% for a full boat system.

One other thought: For those who tend to hold back on exhaust mods due to warranty concerns, it’s been said many times – it doesn’t void anything unless the dealer can directly attribute the failure to the modification.

Thoughts?

Riad

Easy to solve... just dyno at an independent shop before and after. That should solve the dispute.

MoneyBiz

Try to do the muffler, headers and intake + software and/or u could do a search a see what the others that have done it think abut what the gains are on the dyno and on the street or track...

MoneyBiz

http://www.vividracing.com/catalog/p...ducts_id/24313
here it says u can get more than 10% gains with software and cai...
so if you could get another 10 w the headers and muffler that's 43 hp for a total of
368...

robbonds

when i had my boxster s i got right beside another boxster s with headers, intake and chip...i beat him off the line (i think i just got a better launch)...we both went through the gears very aggressively...he pulled next to me then went right by me...i could not keep up - he kept pulling farther and farther away from me...no doubt his car was faster than my stock boxster S

i have a 997S with headers, intake and chip - i have yet to pull up next to a stock S to see if the results are replicated on a 997

not even a dyno is 100% accurate - temperature and humidity change etc...

looking forward to the day i can really compare against a stock car on the road..if we bother are going 60 in 3rd gear and punch it the truth will be told

Rick in Colorado

Good point, but probably not as practical as with an H-D. Virtually all Harley dealers have in-house dynos - and, as I mentioned we're a more dyno-centric group. Most importantly, if I blow up my H-D on the dyno, it's a $2K rebuild. If I blow up a Porsche it's...I don't want to think about it. Having said that, I'd also like to hear the results.

Synergy, weren't you going to post your before/after on your AWE system, or did I miss it?

icon

who said there was no performance gains possible with after market exhausts?
never have understood why harley cruiser owners would be concerned about
mods and dynoing their bikes since they arent built for performance?

Eggplant Cab

Robbonds
The problem with testing against another car is that you didn't go against him before to get a baseline. Out of the box engines can differ a lot. My 1st Porsche 911 targa was dynoed at 261 rwhp with 8k miles. After exhaust (with cats intact), airbox and chip, it pumped 276. The 2nd 964 had 255 at 4k.
So your method is abit inaccurate. A dyno takes out the driver and other variables except environmental. Even if there's a 20°F or 10% humidity change, the dyno is accurate to show an increase or decrease to a point.

MoneyBiz

Maybe for the sound?

Bob Rouleau

I am very skeptical aboout claims made by aftermarket exhaust system suppliers. I have been burnt by several in the past. Great sound - yes. Weight reduction - yes, power increase - NO! In fact at least one was a power reduction.

More noise does not equate more power. Since the 993, a cat-back exhaust has had a lot of trouble extraing more power. I have read that Porsche uses noise cancelling techniques to meet sound pressure levels without overly restricting the exhaust.

Headers are another matter. They usually deliver a power increase although a retuned ECU may be needed to get the benefit.

It is also interesting that Porsche makes no claims of added HP with the PSE. It sounds nice but no power gain. How is it that non factory, low volume suppliers manage to extract more power ... or, are they simply promoting?

I also find it interesting that the 996 GT3 makes only 9 HP less than the 996 GT3 CUP car which uses high flow cats and no mufflers at all. Nine out of 380 ...about 2.5 percent. Just another data point to consider.

Best,

Rick in Colorado

You think that driving a P-car is fun, try doing a 5th gear roll-on on a 100+ bhp/lbft Fatboy - the earth trembles beneath your wheels. The sensation of raw power is unbelievable. And…my Harley goes from 0-60 faster than a turbo.

Bottom line: horsepower is additive. Hell, I even souped up my son’s Go-ped. Go figure.

icon

they dyno for sound?

ridden all types of motorcycles!
if i were going for performance i would get a sportbike.
a 250 could lap your harley!

Rick in Colorado

Totally agree, but it sure wouldn't have the style. Ordinary citizens walk by sportbikes without a glance, but they positively drool over well turned out H-Ds. I can't exactly explain it, but everyone knows what I mean.

Eggplant Cab

Dunno about that. Lotsa people noticed my Ducatti Monster more than my heritage softtail. Now I just have a moped and a mountain bike

mdrums

Rob I live in Tampa so when my C2S Cab arrives in August I will take you up! Sounds like fun!