I did the spinbrush mod yesterday, and I am very pleased with the results. I can do
real drifts, and if the tires didn't spin so much it would probably be faster than a S2, but its about 3 times louder. Torque is amazing, and the motor doesn't seem to get hot (maybe because it was from a consumer's toothbrush

)
To anyone who has and Xmod, spinbrush, extra Xmod motor (for wires), soldering iron, skills to solder, and either a pinion puller or a high-temperature flame of some kind (to get the pinion off of the Xmod motor, it's glued on), this is a worthwhile mod to try.