Like I've said before, you won't be able to do that with this car. The AWD system just isn't designed to go RWD like you want it to. If you want that, go with an Evo or STi. Since our system is a PTO-style rear setup, we can only throw 50% back to it. Couple that with the understeering tendencies, as well as its weight, and that's quite a bit to overcome.
Look into a 2-rotor setup. You have to rev the living piss out of that to produce any kind of torque. Why do you think some FD RX-7 guys throw the SBC 350 in the car? The motor is all aluminum, you wouldn't be shedding as much weight as you think. Yes, it would be lighter, but not by enough to justify all the custom fab work.