You wil not have a good time by just dropping a hotter motor into a rtr.
If you do this, you must match the gears to the motor. For instance, most cars are geared 9/27 or so. Putting a Rabbit, Carrera or similar, you will lose all brakes AND need at least 10meters of straight to see the performance gain. However, go to 8/27 and the brakes come in and the acceleration will be nicer.
A cheeta...I recommend something like 8/30