i have a dc 4-1 header to 2.25" piping back to a stock muffler. i have no cat. you cant really hear anything till about 3k when the stock muffler gives a shitty rattling sound (i think i need to replace the muffler bearings ) then above that its not really that loud, just a mean growl from the cold air intake.

if youre going to get a new muffler i suggest an es oval muffler. i have seen a couple cars with these mufflers on them and they are a very nice muffler, ask anyone who owns one. i know neil (getrdun) on the boards has one and im sure he feels the same way i do about the muffler.