Hi. I recently upgraded my 1996 mercruiser vortec 4.3. My current prop is a 13 3/4 x 21 vengeance. The upgrades added 100 hp over the stock 190 hp and I'm figuring a 24" pitch is what I will need. The alpha outdrive has a 1.81:1 gear ratio and the boat is only used with a light load. The boat is...