if you leave your under drive pullies on when installing a blower how much boost would you lose?couldnt you change the blower pully to make up the differance in what you would lose?
sorry im not answering your question exactly but i've aways heard that you want to keep the stock pulleys on .... even so why would you want to have underdrive pulleys on your car when you would have to comenpensate in the situation you describe for more money?