High flow cat/test pipe

[aznob588]

I have a Redtop in my 89 and my car used to backfire a lot due to retarded timing but that has already been fixed. I was just wondering due to the backfires I think my stock cat is all burned up inside. I also have 3 inch HKS downpipe and Invidia full cat back exhaust. Would I gaining some hps by replacing my stock cat with high flow cat or test pipe? I don't care about emission cause I got the hook up for that and I don't live in Cali so the exhaust noise won't matter here in AZ. Any information would help~

[Bryants95240sx]

a high flow cat will be just as efficent as a test pipe and still be nice on the enviroment

[adey]

You would almost certainly gain some by putting in a 3" cat... don't use a test pipe; it sucks for the environment and in the end, will suck for you.