I have a y-pipe, but a modified custom b-pipe. Which size cat am I supposed to get? 2.5" or 2.25"? thanks

 

You probably want one to match the size of the rest of your exhaust. WSP and budget Y are 2.5, I heard stillen is 2.25. What's your B pipe? You wouldn't want to bottleneck a narrower cat than the rest of your exhaust, but it doesn't need to be bigger either.

 

stock is 2.5 most Y's end in 2.5 i think...

 

right... this is what I'm unsure about. Which end of the cat takes priority, pre or post cat. The y-pipe is 2.5", but the b-pipe is 2.25" (stock). The only thing I had done to the b-pipe was replace the resonator which was damaged. I had the guy weld new 2.25" tubing just far enough to eleminate the flattened section, which motorvate.ca talks about in the b-pipe review.
Since I just paid to have this resonator put in ($40), I don't want to redo the whole b-pipe just to "match" my exhaust system.

btw, I'm not sure if it was replacing the damaged resonator, or the squashed pipe section, but I know my car now has more bottom end power and is more responsive.

More suggestions and knowledge are appreciated.

 

all i know is i have a 2.5 b pipe and it mounted to the stock cat with no problems.

 

is your b-pipe stock? or stock diameter? b/c I might be wrong in thinking that stock dia. is 2.25"

 

mine is aftermarket.

 

bump... lookin for people w/aftermarket cat and stock (or stock diameter) b-pipe