I've found the Supra to be fairly stable by itself, but with any lower gear ratio and a burst of the Nitro's, it'll run a lot quicker. However, with that, you also want to look at at least a sports or better suspension system, this baby will rock like a cradle if you don't take care of that. Make sure the dampeners a about average, and the shocks themselves fairly hard. That'll give you the most stability.
Be careful though, if you're not a very experienced driver, I'd suggest turning traction control to 1 or 2 if you mess with the shockies.