Can anyone give me a list of small things I can do for hp gains on my 2000 civic si like some bolt ons or anything like that?

 

You can install an intake, exhaust manifold, and exhaust kit, but you will only see like 5-10 hp at most from that.

How much money do you have to work with? What are the current mods on the car?

 

Everything is stock except for cold air intake... I'm about to drop a stage 3 clutch and light flywheel, along with 4-1 headers and 3in piping to the back... what kind of intake manifold would be good to go on it?

 

And the biggest outlet for headers I can find is 2.5 is this going to hurt hp gain or do i need to have it streached to a 3in to match up?

 

If you are just doing bolt ons, 2.5" should be fine I would think.

 

3" exhaust is way too big for a bolt-on engine... if you plan on boosting the engine or throwing nice big cams in it later on down the road you'll be fine, but if you don't plan to do either, I'd say look for something no larger than 2.5". A lot of people run a 2.25" exhaust on all-motor Hondas.

*edit: Also, look into Skunk2 and Edelbrock intake manifolds. I believe Edelbrock makes B-series intake manifolds. If you really want to spend some money, try a Bisimoto intake manifold.