Ijust bought those for my Tiger like 2 weeks ago and they work great. The bolt right in using the stock pinions and even come with 2 other sets 12t and 14t so you can adjust the speed. Personally i like the stock 10t pinions alredy on the motors.. Its a lot slower but has a ton more torque now and can crawl along at a snails pace while still going over large objects.

The only problem i had was that the one on the left TUmoves the motor back a bit and i no longer had enough clerance for my battery packs and my speaker box so i had to remove the speaker from the stock box and make a new one to fit.