Ah, a man after my own heart. I've gone down the same path, and have managed to remove a significant amount of unneeded (on the track) weight. Here are some of the things I've done:
- Removed rear seat, as you have
- Replaced seats with racing seats
- Removed passenger side air bag module
- Planning to install a lightweight, non-airbag steering wheel
- Removed the cruise control unit
- Removed the windshield washer reservoir (it was full of fluid, and weighted a whopping 12 pounds!)
- Replaced the hood with a fiberglass hood
- Removing hood struts, and looking into lightening the hinges
- Removed the front bumper
- RS Barn Motorsport 18-lb flywheel
- Lightweight Enkei NT-03 18" wheels (pretty sure they're lighter than the 17" 10-spokes I had before)
- Removed the fog lights (kept the lenses for now, but will eventually put brake duct scoops into the fog light openings)
- Lightweight cat back exhaust from RS Barn
- Removed the spare tire, tools, and pump
- And the crowning achievement (at least in terms of the amount of work involved), I'm in the process of replacing the pop-up headlights with fixed headlights
For now, I have a cheapo 27 lb conventional battery from Autozone, and am researching replacing it with something even lighter, but since I still need to drive the car on the street some, I need something that won't let me down on a cold morning. But here in Austin, it never gets much below 30F, so I might be able to get away with something smaller. And since I've managed to get so much weight out of the front of the car, I'm considering replacing the hatch glass with lexan. I will also probably do something with the sunroof - the power operation has never worked right, so I'd like to tear it all out, and replace it with some sort of manual operation, but I haven't gotten to that yet.
Is there anything you've thought of that isn't on my list? Good luck.