What boat do you have? I settled on a 29 tempest for my boat however I did run a 28 raker and raker II. I am no prop expert, however the II ran the same speed as the raker, but with less rpms and the holeshot was incredible with the raker II. Visually, it looked as though the raker II has more cup than the raker, which would explain the rpm difference I experienced. Just was not the right prop for my boat.