What is the size of the pipes you need to get when you get a cat back or does it matter as long as you have a sizer peice

 

Guess you haven't checked out the very informative and worthwhile post that CLEAR posted about catbacks...

You can go with a 3" pipe...a 2.75" pipe...or a 2.5" pipe. Or you can stick with you factory pipes. Technically you have a cat-back exhaust...just a factory one. Why? (Here is my Auto 101 for today).

A cat-back exhaust is:

An exhaust system that goes from your cat to your tailpipes. Hence the name...cat-back. This includes everything from the cat...the I-pipe, the S-pipe/bend, muffler, tailpipes, exhaust tips.

I don't know what a "sizer peice" is though. I know you'll probably ask this too...so before you ask which size exactly, take a look at CLEAR's post entitled "3 " catback = not enough back pressure? "

 

Yeah.. on a v6 a 3" catback would kill your low end. I would go with no bigger than a 2.75" and then you might want to make sure you have more air coming in before you really worry about it.