Tim, have you ever thought about selling your Prowler? Just curious! Long term owners tend to keep them forever! How many miles on yours?
I used a 6" pulley on the drive shaft, could have went up to an 8" before I'd worry about hitting something on the trail. 3 to 1 ratio seems to provide ample charging. I check my batteries at the end of a day, and both are in the high 12.7 and up area. I run with my lights on and belt fan running on the street, and have not seen any low voltage! Great project, glad you mentioned that you were going to do yours, give me the spark to finish mine!