Stator wire gauge

I have a shindengen sh775 regulator that I want to replace the stock one with. There are 2 wire sizes of connectors offered, awg #10 and awg #12. I need to know which to order. The voltage occasionally spikes to 17v (I have added a voltmeter on my dash) and outpur seems low. I added a 20watt strobe on the roof and cannot run the headlights (switched to LED) even by themselves. They are 20watts each. I checked the stator wiring and tests fine. Stator plug looks good, not corroded. I have not found the other end of the regulator plug yet, still looking. I will try to trace the wiring coming out of the regulator. This is on my Kandi Viper trike that someone else put the Silverwing on the back of. Things were relocated as needed and also spliced as needed. As to wiring issues, Speedometer works but odometer does not change. That's another topic for another day.