It depends on what your end goal is. A fast cart with a lot of torque or a slower torque monster, or something in between.
The 22" tires is costing you about 18% in torque, but the 400A controller is upping torque by 33%, so the net gain over stock is 15% and a 36V cart that does in the low to mid 20's.
Going to 48V will give you an additional 33% more torque and some more speed. (48% more torque than stock)
Going to 8:1 gears will up the torque by and additional 36% and cut the speed by a similar percentage.
A high torque motor will also increase torque and reduce speed, but I don't know what the ratios are.
In any case, you may want to consider installing Heavy Duty hubs before the splines in the existing one spin out and damage the axle splines.
