fastbs: Do the pcb swap with a cheap clone and you will be impressed. I did that on my zip with the dual battery mod and it will easily do doughnuts. Now performance is much better than my bits. It will easily run on carpet. It does take a little skill to do the swap (draw pictures) so the steering & directions come out correctly. Stock zips are slow, but with mods they are amazing and the car still looks stock and can even use the pcb cover. Good luck.