I will add onto this. 6000 + is what you want to run. In theory the higher MAH the longer your battery will be in a higher volt range and that = more power. So simple answer is higher mah the better. Now to make things more complicated is the IR or internal resistance of a battery. I have been running 6000 mah batteries because they had a lower IR then most 7200. Lower IR means more power going to use or more efficient vs just wasted on heat. Most battery manufactures do not list the IR of a battery though. So the safe route is a higher mah pack. You will need to add weight to most cars regardless of 6000 or 7200+.