Cas, it's easier to find an aftermarket clutch bell (HPI threaded 2 speed works, I think Popper tried it), but you've got to keep the same ratio difference between 1st and 2nd as stock...I think the stock is 16 and 21 (or was it 20???) so if you want more acceleration, you'd have to trade off a little top end and go to a 14 and 19, or 15 and 20 (assuming I'm right about the 21 2nd gear...)