I'm looking to get my downpipe fabricated soon. I was wondering what size downpipe I should get as well as cat. Currently I've got the GReddy EVO exhaust, which is 2.36" in diameter. I'm going to be running a 14b turbo on a b18b, at about 7-8 psi..so I'm not going to be boosting over 250 hp anytime soon.

Would it be best to match the downpipe size with my b-pipe size? Or would it be better to go with a larger sized downpipe, maybe 3"?

And if I were to go with a 3" downpipe what size cat shoud I get, since I would have to go from 3" to 2.36"...should I go with the something closer to the diameter of the downpipe, or something closer to the b-pipe, or something inbetween?

Thanks