I'm a new member and I just bought a 2000 Honda Civic SI.
Here's the list of mods that are on it:
Cold-air intake, header, exhaust, AEM fuel rail, wheels, short shifter, tokico coil-overs

I was wondering what are some other mods I could put on that are low cost and don't put your engine under a lot of stress. Is getting your heads ported and polished a good idea or shimming the heads? What about throttle bodies and intake manifolds? Give me some suggestions!

 

Intake manifold, and throttle body. Look into Skunk2.

 

if it doesnt already have them, polyurethane bushings for the shifter will tighten it up and make it a lot easier to use. and i would hold off on the intake manifold at least until after a set of type r or stage 1 cams. and the appropriate valvetrain.