Here is the controller. The mosfet's look like their 70 volt 80 amps from the datasheet. They should be able to handle more amps than stock.
The stock controller is a 18 amp controller.
There is a shunt resistor that limits R003 the amps.
If I replace it with a R002 it should give a nice boost power going up hills.
I also ordered a R005 to put in parallel that will take the finial value to .001875 This will give just a little more amps and be a simple to just solder it on top of the other one.
There are lots of people doing this type of mod out there.
Here is a good example.
http://www.bergerweb.net/xb500/shuntmod.shtml
This mod will not really increase top speed but should give more torque.
To increase top speed I need more voltage or a better motor.
I want more torque for hill climbing.
I am going to order a R002.