Stock M20 exhaust specs?

[Earendil]

Forgive me if this info is hurried someplace, but my searches didn't bring it up, and there isn't an appropriate sticky for it.

I'm looking for the stick exhaust specs (single/double) and diameter for everything from the headers to the muffler. I can find suggestions for M50 and S50 engines, but not M20s!

I ask because my buddy and I each have very different hacked up Frankenstein systems that the PO (or his mechanic) decided was best. If I take this to a muffler shop and they aren't geniuses (and in small towns, not everyone is) I want to know what I'm talking about.

Bonus question: presumably a cat is the primary bottleneck in a stock system. If the cat were removed, is the stock pipe diameter still good enough? Or would it become a bottleneck?

Cheers!

[325ix]

There is really no bottleneck in the stock system. The benefits of a new exhaust are sound and weight savings. Go with a 2.5in. all the way back. The stock system is something like 2 1.75in. pipes on the later model 325's.