Don't know much about this stuff: I have a 2015 RT 188 Ranger w/ 115 Merc Omax (2 stroke). 6" JP, 21p Lazer II prop, at WOT getting 57 mph / 5250 RPM's. I'm happy with the speed but does more RPM's mean More speed? I believe the motor max RPM's are 5,800. To get more should I raise the JP, lower the JP? I also have a 20p Lazer II, should I try that? Thanks!!