best bang for your buck will probably be a sidewinder 4600 or 5700. they can be had for about 120 on amain hobbies. i run a 4600 in my cyclone and plan on getting one for my cyclone. the motor has gobs of torque for nice long drifts and excellent wheel speed. the novak systems are also good but seem to lack the power throughout the rev band that the mambas have due to the mambas having variable timing i.e. vtec versus the locked timing of the novaks. the novaks do have better punch off the line however.