This might be a dumb question, but something doesnt seem right here. Help me understand. I was looking at the pulley drive ratio chart on the BDS site and it shows the pulleys I have (61 and 54) to be 11.5 under driven with the big one on top. But 13 over with the big one on the bottom. How is that possible ?? Is there some kind of new voodoo math involved or is there a drive ratio change inside the blower and there comparing crank speed to the blowers rotor speed ?