Depending on how many miles you have, you should probably make sure all the recommended maintenance is up to date (just like dustimus says ) before you do anything.

Air filter + removal of intake resonators could be your first thing to do to let your engine breathe a little better (k&n filter) until you're ready to plop some cheddar into it. Team-Integra.net is a great source IMO (preach dustimus PREACH) not only for general info (specs and such) but in-depth articles on just about everything Integra.

Oh, and there are pleny of people to wave the bullshit flag too so you can feel pretty confident the info you get is reliable. (just dont forget about search)