I just recently installed a new 300hp merc 350 magnum horizon engine package with a bravo 1 1.5 drive and i dont know what i should be reving. I have a 15x17 rh 3 blade aluminum prop and the rpms go too 5000 rpms. The boat takes about 10 seconds to plane when the throttle is pushed all the way it only goes to 4000 rpms before it planes down and goes 5000. And it looks like im not getting a very fast mph at only about 30. Old engine was a 240 hp cobra which went 33 with a 15 1/2 x 15 prop. How can i go slower with 60 more hp? And what prop should I be using?