It all depends on how much you're willing to spend and how much comfort, convenience and security you're willing to give up.
Heavy single items include side impact door beams, bumper reinforcements, glass, battery, probably muffler, then the obvious spare tire and jack.
You're not going to really save any weight unless you get radical. If I was in a different financial position I'd pick up an older AWD, build a stroker with tubular manifold, a lightweight turbo, real short exhaust path with a real light muffler, a small gel cell type battery, strip the interior out to bare metal, lightweight race seats, a real flimsy fiberglass dash, roll cage, pull the bumper reinforcements, then mold the entire front clip, doors, and hatch out of carbon fiber. Make some plexiglass side and back windows and then put some lightweight 15" wheels on.
That'd have to potential to be a quick race car. It'd only be streetable enough to drive to the track but hey, who cares, it'd be a second car.
On a street car you can save a few pounds here and there but IMHO there's not much worth the sacrifice to give up. I like my stereo, sound deadening, a/c, p/s, p/w, p/l, safety and durability too much.
It wouldn't hurt to pull the sub box, amps, back seat, spare and jack on race day though. But I'm gonna leave that to the Honda boys.
Go Fast With Class.
