i use to use a 40t 48pitch pinion in my tc3 when i had a 13.5 in it :P
with the stock 72t spur.
Speedtech will take care of you...
Pinions
http://www.speedtechrc.com/store/ebp...?catmainid=502
Spurs
http://www.speedtechrc.com/store/ebp...?catmainid=392
My tc3 has the xtreme racing carbon chassis so i dunno what the stock cam/motor mount setup would fit but you can easily obtain a 40t pinion and a65t spur from speedtech and that puts you at 4.06 FDR so just get a smaller pinion to into that guy's suggested 4.5-5 FDR range...
