In a nutshell the Stillen is a bit louder for my personal taste but others on several occasions have told me how they liked the way the car sounded. Two people followed me and stopped me just to say how much they liked the way it sounded. (have headers and high flow cats) If you keep a light accelerator pedal and the engine below 3000 rpm, the sound is very reasonable. Go over and it's louder than my particular tastes warrant.
My personal feeling is virtually all the aftermarket exhaust system will be very close performance wise. If you really think about it, they are 2.5 inch mandrel bent tubing, dual resonators and dual mufflers. Some eliminate the resonators but at what penalty? Loud doesn't necessarily mean more power and on two occasions we dyno tested my Corvette (stock and heavily modded) regarding open headers vs dual 3" exhaust system with resonators and mufflers showing absolutely no power difference.
Think things like X-pipe vs H-pipe, 2.5 vs 3" exhaust, etc. are way overrated as header design is also.
Bought a super expensive ($2K) set of stepped tapered headers with merge collectors that the mfgr said would produce 20 hp over conventional headers. Nope. The car dynoed the same as my cheap Hooker Super Comps bought from Summit.
Called Larry Meaux who writes dyno simulation software and whose heads have 28 NHRA records. According to Larry, it's hit or miss on header design with some designs working a bit better on some engines and the same design on other engines not doing anything. In all his years of building race engines, he has never seen over a 1% hp difference in output from header design.
Stillen quality.....sucks, but they are pretty cheap as compared to others. After the hassle of making them fit, I'd not buy them again.
Last edited by Denny McLain; 09-28-2009 at 09:16 AM.
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