I have a 2007 chaparral 204SSi with Volvo Penta 4.3GX1 SX, factory 4-Blade aluminum 14x21 prop. With full tank of gas and 4 adults the boat will not plain unless at least one person moves to the bow of the boat. I have been told I need to lower the pitch to correct this, however, that will increase the RPMs on the engine. The recommended RPM is between 4600-4800 RPMs. Took the boat out this weekend and WOT is already running 5500-6000 RPMs, so lowering the pitch seems like it will make that even worse. How do I correct this and what size prop should I consider?