IMO, just keep the stock gearing because the OS 18tz has plenty of power for super quick acceleration. The ED transmission is also desiged for a 1.8 - 2.0mm split between the front and rear foam tires. Without a split, the ED will be harsh on the belts. If you are bashing, just use soft rubber tires, and softer springs in the rear. Also consider using a diff or spool in the front instead of the stock one-way so you can have 4 wheel braking.