I know with the magnets on Etek motors you can adjust them to tune the motor up. Voltage can help but with limited battery load we can carry (73 pounds of lead acid) I don't really see the point in changing the voltage on my car which has a 24 volt system. I'm more concerned with how many watt hours (or amp hours) I can get from my batteries at each race or test I do. If it were an actual road going car then I would get as much voltage for a battery pack that I could afford and fit into the car I was using. Most of us do run 24 volt since it's easier to deal with not just from a simplicity standpoint but its less stuff to go wrong compared with 48 in my opinion. I know some teams and cars that do run 48 and they have had good success with it. One person who comes to mind is Kirk Swaney from Albany, Oregon. He could help you out if your experimenting or planning on trying a 48 volt setup.