One tooth may help, if you're spinning too much now, gearing it down will only make it worse. Normally with the pipes you would go down one because of the extra rpm's. However, this sled is geared short enough stock, I have one, and in testing found out it runs out of gear stock, so you may be fine with the stock gears. On the stock unit it ran out at 99.5mph, I geared it up and it ran 101.8 in the same distance. So I would leave the gear alone for now, and work on getting some better traction. You may try lowering the engagement a little, giving it a little more belt deflection, what's it at now.