[suicideneil]

46/13 comes out at 36mph.
46/17 = 48mph
46/19 = 54mph.

I think a 13-14 tooth pinion will give you plenty of speed for racing with the 46t spur, but for nitro killing I woud think a 60mm motor might be better for more torque to allow the taller gearing work better; 48mph isnt too bad, but 54mph is a little much for a 50mm motor in a... 7lb buggy? I dunno how much it weighs or its size.