high flow catalytic converter

hey guys
i already ordered my headers, intake, struts, and halogens. my friends keep telling me the headers aren't gonna be very useful because i'm keeping my stock exhaust (no more cash). he suggested i get a high-flow catalytic converter ( i don't want to gut mine). i was wondering what the diameter of the stock exhaust was, and what would fit?? i was looking at: http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=33629&item=2462805335 and i'm not sure if it'll fit. here are the "specs": Size: 3.5" L w/ 2.5" inlet & 3.5" inlet

Hope you don't live in an emission state. You won't pass emissions since that is basically a test pipe. If you want to pass emissions go Carsound or Random Technology.

nope, no emissions, would it fit?

Why have a cat if it doesn't pass emissions? That's pretty much the only point of a catalytic converter, otherwise we'd all have straight pipes.