I'm assuming that your new car is FWD. In that case, DON"T DO IT. FOR THE LOVE OF GOD DON'T DO IT!!!!!!!!!!!!!111!!!1 FWD trannies are not cheap to get rebuilt. And on newer computer controlled transmissions, the erbuild will be about 2500 (for instance my dad's 1998 Mercury). On my mom's 1994 Cavalier, it was 1500. These transmissions weren't made for that kind of abuse.
If you want to do this, buy a camaro, mustang, or anything made before 1972. The engine makes boatloads of torque, and the transmissions are tanks. And if they do break, they are cheap to rebuild or even buy a remanufactured trans. A remanufactured C4 with a performance build cost my friend 700 bucks (and that includes labor) 3 years ago.
so for the love of your car, stop.