This past weekend i installed the JDM R header on my JDM b18c, what cat do i need to get, cuz right now im running a straight thru design, JDM header, straight pipe, and straight to the apexi n1 exhaust...its too damn loud right now, top end is good as hell though..u can definetly tell there is no restriction at all...Does anybody know what cat i can use to bolt up to the header and my exhaust..Thanks!

 

I think your header is 2.5" and your exhaust is 2.25"... I'm not positive about the eexhaust though. I'm mating a JDM 4-1 to a ITR cat-back via a 2.5" Carsound cat and then a 2.5"to 2.25" adapter from SMSP.