Im not familiar with that plane, do you have any idea of your amp draw on your current setup? DR.Kiwi is pretty good at giving advice in this area so mayby he'll chime in, Im figuring that you could run a Thunder power 2100 pack and be safe on the amps, Tanics would deffintelly handle it but are harder to find. As for cell count you have two choices with the speed 400 and one is 2 cells which gives 7.4 volts( a deffinite drop in power but with reduced weight it might me alright, or you could go 3 cells 11.1v( which would up yuor power considerably and still reduce weight, but you would sacrifice motor life without proper throttle management) If you ever go brushless like with a himax 2025 then 3cells or even four would not be a problem at all.