What kind of hp/performance gains could I expect if I added an intake/exhaust/header to an 02 ex. I considering buying one, but the se-r spec V looks really enticing for under 18000. However I can pickup a new EX for only 16000. That leaves me 2K for upgrades on the Civic. Let me know.

w/ i/h/e on the EX, you might be looking at around 140 flywheel hp. The SE-R SpecV will roast it all day long. My friend has one, I've driven it, we've put AEM CAI on it and yeah I'd never buy a Civic EX over an SE-R Spec V.

Just buy the SpecV. You'll be alot more pleased, it's alot more car for a little more cash.