2.75 Exhaust so which size cat?

[Dewey]

So having found a catback from a WS6, and wanting to change my cat, I need some advice. The WS6 exhaust = 2.75" right? So should I go w/ a 2.5" Catco or the 3"? Is it better to from smaller out to larger in, or vice versa?

[ March 16, 2003: Message edited by: Dewey ]</p>

[Dan M]

I'd go 3" in and out. Why make more of a bottleneck at the cat?

[Dewey]

I would think that 3" to 2.75" would be more of a bottleneck though. Am I wrong?

[Dan M]

<blockquote>quote:</font><hr>Originally posted by Dewey:
I would think that 3" to 2.75" would be more of a bottleneck though. Am I wrong?<hr></blockquote>

Yeah, 3" is bigger than 2.5". It doesn't matter WHERE the bottleneck is. In this case, in my opinion, bigger is better.

[Paul Collins]

Cats are a bottle neck so my vote is 3" if you must if not an off road pipe [img]smile.gif[/img] but you gotta rev it to make power.

[shortdog273]

Another vote for 3"in/out.

[Arctc Wolf]

3" in/out, but some exhaust shops will be able to modify the cat so the outlet will be 2.75".

[99Camaro99]

you can do what I did and modify the outlet on the stock cat. I have it opened to 3" with a bung at the end. Beware of damaging the O2 sensor after the Cat tho [img]smile.gif[/img]