I'm looking to purchase a new prop for my fiberglass 16'8" 1990 Javelin F&S. The boat was left uncovered for some time before I purchased it and I believe it gained some weight. It's powered by a 89' 90hp Johnson. At WOT with just me it runs 41 mph at 5250rpms. I once saw 5400rpms with much trim. With a couple more people aboard it will only run 37-38 at a little under 5K. It currently has a 13 3/8 x 17 painted steel OMC prop. I raised the motor up as far as it would go earlier this year. It also has a stingray hydrofoil. Should I go with a 13 or 15 pitch to get my rpms up?