If the killshot is faster is just in your application. You have a better timing/gearing combo... Its a proven fact that the illegal D3.5 is the fastest 17.5 motor out there. In carpet pan car racing where motor is HUGE the kill shot is easily 3 laps down.

I'm surprised no one has mentioned the high discharge high charge factor. Putting heat into the battery is also a big difference in power for stock racing.