E-Z-GO makes a heavy duty belt, mainly for the 350cc engine, that will fit any 4 cycle from 93- Present. I forget the part number but I think its something like 733502-G02. Don't quote me on that lol, but its corrigated on both sides and is much stiffer and thicker. If your running a honda though, you might need to go with a shorter belt because the clutches can be closer together than the standard lenght. You might want to try a 3PG engine's belt, its a 3/4" shorter I belive.
Bob