Not to discourage you . But if you just want to go fast go ahead and fix up the gp. I drove one of those g8's and was very dissapointed. With the traction controll off it would barley peel out. I'm sure it can be made pretty fast fairly easy though. I don't know...maybe i was expecting too much for having 400 horsepower?
I know my buddy's old ls1 01 camaor stock was for sure just as fast. And it was a 5.7...
Sorry got a little carried away....