http://www.mercurymarine.com/propellers/prop-selector first place i check for the correct prop. I'm not sure on the jackplate setup as I dont have one but it does seem like the prop may be sitting a little low. Just to compair, i have a 16.5ft lowe aluminum boat with a 90 mariner, running a 23" pitch aluminum prop and I max out, light load, cold air at 45mph and I think 5350-5400rpm. If i were to change to ss i'd probally go with the 22" lazer 2 like you have. So if in the end you do change up your prop and get good results with a smaller prop, message me as i may be interested in the 22"