99 Johnson 150 HP with 13.5x23 Bass Renegade 4 blade on 17' Sprint bass boat only get 4,300 to 4,400 rpm at WOT. If I purchase a Raker with same pitch will I get a better rpm and increase in speed? The manual says the mid range for this motor should be at 4,500 to 5,500 rpm and I'm getting lower...