I'm almost positive Curb weight is the weight of the whole car *d'oh* including all the fluids (fuel, coolant, wiper fluid, etc.). I'd say just run the car always with 1 gallon of fuel and lose a few pounds off my ass for an extreme lightweight car. The person you're racing won't know what hit 'em!
Yes, for a 250% increase in torsional rigidity. The car didn't get heavier for no reason guys The GC8 chassis vault tight and very stiff and the WRX is much stiffer still. Guess where the extra 100kg came from?