The motors are made to take about 3 volts each if you wire it and power it by the diagrams for the free running model...so the 5.5 from the li-po wired in series was more plus the amps would have been way higher...I thought about hiding the steering servo but I wanted it to be simple...I am replacing the motors with some 180's, Ill post a pic of the ones below...they use them in small electric planes and I have used them before...they work real well and handle alot more power, they will protrude through the motor cases slightly but I think It will still look ok...and they were cheap...I have upgraded to better steering links also and also greased the gears in the lower units to prevent burning those up...hopefully some more people will comment...anyone else have a plastic model conversion they are running? I'd like to see them