I am currently running a 22' hewescraft searunner HT with a 115 Hp Evinrude Etec. WOT is only at 5200 rpms. I should be getting 5700-6000 from the mfg specs. The current prop is a 15 x 15. I want to be able to run more rpms for better efficiency. Each step in pitch will get me 200-300 rpms difference. Should I adjust the pitch or the diameter or both? Any suggestions? Thanks.