So I just bought the Calsonic GT-R for 950,000 credits. It's not that fast (considering the price) but it handles pretty good. Is their any tuning that can be done to these types of cars to make them any better?
You should make your own. The basic stuff that can be change easely is aero, braking power and transmission setting. For the rest, check the sticky on the tuning part of the forum.