Will a 20 amp battery go faster then a 10 amp battery?
Look at it this way.
Voltage is speed amps is distance. A 48 volt battery is faster then a 36 volt battery. The maximum a GM motor will go is with a 48 volt battery. If you go higher then a 48 volt battery you will blow the controller. If you increase the amps. You will go farther, not faster. A 48V20AH battery will go twice as far as a 48V10AH battery, it will not go faster.