LiFe battery for sure.
Lipo must use voltage regulator, and the problem using lipo in nitro car is the chance of getting involve with problems I describe below :
1. Cheap made voltage regulator produce low amp, which is not adequate to power high amp servos.
2. Cheap made volatge regulator probably dont last long.
3. Extra wiring and connections.
4. Fuel spills mishap >>> electrical problems.
5. Voltage regulator clutter the car's look, like in the foto above.
On Road : Xray NT1 , RX8 , T4 || Mugen Seiki MRX4-R , MTX4 , MTX3 prospec || Tamiya M03 , M04 || Top Racing Sabre FD2
Off Road : Xray XT8 || Hobao Hyper 8
Radio : Futaba 3PKS || KO propo EX-10 eurus