gunlover05

What is the real sound or performance difference between a euro premuffler and a cat by-pass? Anyone have a preference?

I am planning a SW chip, either premuffler or cat by-pass, and a M&K 1 in 1 out soon.

Adam M

Performance wise they are probably the same. I had the euro pre-muffler (to replace the cat) when I had the 3.2L in my 84 911. It sounded pretty cool. I always figured if anyone asked (cops, etc.), I'd tell them that it was the cat because it was about the same size as the cat was.

BHMSC

I have the FabSpeed pre-muffler and (still) a stock muffler on my '80 SC. I went with the pre-muffler (which, to my eyes looks like an old-fashioned Cherry Bomb - but in T-304 stainless) because I heard that the straight pipe cat bypass' often had obnoxious resonances. I'm pleased with the sound (mellow and not that loud) and what seems like slightly improved performance (FabSpeed claims 7 hp but I'm a skeptic).

If I had my druthers (and was willing to spend $1500+ to replace a perfectly functional exhaust system) it would be SSIs and the factory sport muffler - especially now that I'm "historic" and no longer have to go through emissions testing.