For 4S setup I use trakpower 4900's and SPC 8000's :
http://www.specpointbatteries.com/in...p?productID=61
Both packs work well, but the long run times of the SPC are amazing.
Gearing is 20/68 or 20/64? Not positive on the spur. It made a good balance when switching between 4S to 6S setups. 6S was still fast, but controllable.