Corse-r I have used spur gears as small as 78t 48p on mine with no problems.
Also at the Chicago show I spoke to Jared Scott from Fantom Racing and he was telling me that Fantom was going to hook up with X-Ray for their team here in the U.S. He`ll be switching from a Tc3 to an Evo-2 with the c hub suspenion for all tracks.