Originally Posted by Eddie_E

15 out of 23 racers at our track have been running the SMC 1S lipo with either 13.5 or 17.5 motors. All the rest say they will switch after the Nats.
The Novak 4cell and Havok both work without boosters. The Speedpassion LPF works without boosters. The Tekin RS currently needs a booster, but the next software should make it work without the booster. The Tekin is by far the favorite at our track. The JR servos seem to run slow without a booster so I'll run one either way. The Futaba 9650 users don't seem to notice as much, but still a bit slower.
If you are allowed to run the Lipo, do it.
If it were legal to charge a lipo in the car, A person running 13.5 could plug in and charge immediatly after thier heat, before going to turn marshall as there is no heat in the battery at all.

The best estimate is that the 13.5 is around .2 seconds a lap faster than 17.5 4 cell and the 17.5 lipo is .6 slower. (no weight added)
Gearing is a bit higher than were used to.