tranny for g2r ????????

what are my options? it seem this board is flooded with great ideas, however i haven't seen a clear "winner" in this department. if i'm gonna race what exactly do i need. i'm using mamba max power for racing, but i don't know what tranny and gear combo would be ideal. And what about the availability of the choices, is there any thing readily available. I've had the g2r partially built, just minus electronics, and tranny. it has been this way for months with no progress, please help me, thanks for any help:032: