4S with at least a 30c rating ive been running it on my 2200kv motor for about a season and a half if its hot outside it can get warm after a run but not where its hot ! Still has decent punch .
Gearing also has the most affect out any C" rated lipo. I say that because i can go a tooth down on a pinion and with a 30c 4s lipo it can feel like i have massive torque off the line and to jumps. But than again i was using a big spur gear also.