Or do I want the 5S

http://www.hobbycity.com/hobbycity/s...idProduct=8585

Yes this is the 6s batt I use, runs cool n cheap.U may want to turn down ur EPA if u use a 2200kv motor with 6s as by 10mins ur motor will b 80degrees. That's the max temp a motor can go safely

I'm using MMM 2200 combo with 6S (2x 3S 5000 25C) Zippies on my ST pro, and it has been great.

I only have it geared for 52 mph so temps are decent. Could be geared higher but would risk over heating if driven too long. Besides, it is plenty fast enough as it is; I barely go past 3/4 throttle.

Although it wont get you 70mph, you'd be happy w/ the 2200 combo on 6S. You'd have a lot of torque and it'll feel fast because you'll hit 40mph+ in an instant provided you have traction.