A lightweight FAL rear window? I think that saves 40-60 lbs, but I'm not sure how street-legal that is. You could go with a carbon fiber hood and get it painted, which would save a bunch of weight if it's a good one. How about reducing unrprung weight, like with wheels, brakes (aluminum Spoon calipers?) and the like. Or are you trying to do it just by removing stuff? If that's the case...uh...start drilling holes in the doors? Other than what Erik B said, there's not a lot of stuff left on the car.