what is all this stuff that i hear about and extension pipe or something that you need in order to put a catback exhaust on a 98 civic dx 2dr cpe? wouldn't the ex catback work on it? b/c i was plannin on just buying the ex 2dr exhaust setup and use that? i have bought a header and high flow cat already and was just wondering what else i would have to buy if i get a catback exhaust for it to fit on my dx?