I just bought a 14-1/2" x 18" 4 blade aluminum prop from iboats and it gave me 5 more MPH. My 150 Optimax's max rpm is 5700 and this prop will spin 5800 rpm with 2 people in our 22' Tahoe boat, but usually there are 4 or more people along so I think this will be fine. (My old prop is a 14-4/5 x...
