The 1.76 is a welcome upgrade. If you only want to go no more than 25 mph then you won't care if you prop down to a 12.5"pitch, you'll have torque to spare, but, I don't think it is necessary. You can sport a 15" pitch prop, at a lower elevation with 4-5k lbs ballast and be fine. It is essentially a balance between speed and torque, finding that happy medium. I would not go over 15", other than that, it's a matter of preference.