Menace2Society

I'm not certain but what's the size of the stock cat and exhaust piping for a 99-00 Si. Also just wondering but if I get a bigger aftermarket exhaust,headers,downpipe, will I need to upgrade my cat to match the piping size too?

peaksi

my apexi n1(60mm) which is about 2.25in bolted up to my stock cat.. and i know most aftermarker headers bolt up.. like dc-sports and kamkize. if that helps.

. a d a m

Your exhaust is only as good as the part where its diameter is at it's smallest. If you were to get an aftermarket header and cat back, you would probably want to get a test pipe or cat of the same diameter.

pdiggitydogg

I disagree with that....
Lots of people make gobs of power, still retaining the factory cat.
I bought my beater pos ed6 without a cat and hate the damn thing - stinks like *** and is loud as hell

btw, factory piping is 1.75"
and its "header" singular.

. a d a m

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by pdiggitydogg &raquo;</TD></TR><TR><TD CLASS="quote">I disagree with that....
</TD></TR></TABLE>

People might have made gobs of power with factory cat, but thats a true statement.

pdiggitydogg

i guarantee you that swapping out the stock cat will only give you minimal gains

ARMED

and its loud as ****....