[jhautz]

If you just want the bigger pinion for a cheap as possible then you really only need the revo spur adapter. Putting thr smaller spur gear on leaves alot if room for a bigger pinion. That would be the ceapest route.

Every tooth you take away from the spur gear leaves room for one more tooth on the pinion. Going from the stock 49T spur to the revo 40T gear let's you go up 9 teeth on the pinion. The smaller revo gears will give you even more room for bigger pinion.

When I bought my adapter from RCM it even came with the 40T revo gear. Not a big deal, but saved the $5 to buy the gear too.