C5 parameter is the maximum current adjustment. You can use that to limit available power to the motor. If you decide to use this parameter, you'll find each different value available can be split/trimmed 3 ways using C14 to get pretty close to whatever you prefer. Takes some test rides/messing around, but I think you'll agree you can set those lower PAS levels about any way you'd like using the 2 parameters.
An example - I have a MAC 12t geared hub powering my '17 Rad City. It's capable of pulling 1500 watts pretty easily as it's one of the most powerfull geared hubs available. I used C5 to limit available power to about 1100 watts out of a concern for the RAD battery. Internal wiring is all 14-16ga which is not going to handle 1500 watts well at all. Not for long anyway. Once I arrived at the C5 setting I wanted, I used C14 for a final adjustment. Works grrreat!!!! PAS 1 lets me play at around 90 watts, PAS 2 just under 200. Just right for my personal tastes. -Al