does anyone know where i can find the answer to this question: i recently purchased an itr 4-2-1 header with a 2.5" collector(o.d.) i've been looking into purchasing an entire jdm cat+catback, also 2.5"(o.d.) Well, i ran out of money and was wondering if i could stop halfway... if i put on the header and a 2.5" cat, would that fit my stock 94 ls b-pipe? Obviously it would go from 2.5" at the cat to 2" at my b-pipe, which sucks, but i don't have the money for the catback right now. Could i instal the header/cat now and put the catback on later when i get the money?