So if I am understanding correctly, to go to a four blade I would buy a 13.25" x 20?? I haven't seen one that size on the market in my searches. From what I am reading, the four blade provides better cornering (less cavitation) and holeshot which is just what I want. Loosing a couple mph isn't going to upset me too much. Losing 5mph or more would, however. [links]