I just bought some dc sport headers for a 97civic ex. I installed them by myself. I didnt really see a difference in horsepower, but did see a change. Well, is it because i dont have an exaust to get rid of the back pressure

 

You will need to dyno it to get the real picture. I put a header on my zc swap and I couldn't really feel a difference but then again it was a crappy header. lol A header is not going to give you huge gains unless you have other mods along with it. An exhaust will help in conjunction with the header. A header will go good with other mods like headwork, upgraded cam(s), etc

 

reset your ECU, as well, it might help...also header usually won't add $$$ of power unless you are using some super restrictive piece ....but honda did them pretty well...