I just bought a 1990 Arriva 20' with a Mercruiser 350 Magnum and Alpha 1 outdrive. I did an oil change, but otherwise haven't touched the engine. I can hit 58 mph, with the engine around 4500-4600 rpm but it's porpoising pretty bad by that point. What modifications will get me to the 70 mph mark? Is this boat worth messing with? It has a 21" Laser 2 SS prop on it, and through-hull exhaust.
I would really appreciate any advice I could get.