LiPo LiPo LiPo!

[coolhandcountry]

With the weight lost would make it easier on motor to or motors in your case. It is going to push the motors pretty hard though. 3.7 volts a cell at 5 cells on a motor with a 2731 kv. your look at alomsot 50,000 rpm. of course that is unloaded rating to. I think the 4s may be better for you. You could probably step up in gearing for the lose of weight. So you gain the speed that way. That is 4s per motor.

[poconoblmaxx]

I second the 4s packs. You'll more than make up the difference in voltage with the weight savings.

28 sub c cells (2.2oz ea.) - 61.6 oz.
4 2s Kokam 3200 packs - 28.2 oz.

Voltage drop under load is also less with lipos.