I have a 1986 grady white bowrider 20 ft it has a 170hp 470 alpha one drive according to the tach i;m turning 44-45 hundred rpm the prop is a 14 dia 19 pitch. Is the rpms to high for this motor? I rarely go wide open but when i do the motor sounds like its screaming. I don't have a speedometer or a gps don't no how fast i;m going but it dosen't seem to speed up much from 3/4 to full throttle anyway thanks for any /all replies