I originally had the boat propped with a 21 P merc aluminum prop. It ran ok with that but I could only get 52-5300 RPM out if it at WOT and lightly loaded. Switched to a 21p stainless (laser II) and that did not change so I went to this 19P prop. Still not much RPM at WOT difference. Now I raised the motor to the top set of holes(cav plate is about 1in above the bottom of the boat) and still no change in the RPMs but I have picked up more porpoising. I have trim tabs on it an have to run the motor all the way in and the tabs down a bit to keep it from porpoising above 1/2 throttle. I tried switching back to the aluminum prop but now it blows out when trying to get on plane. Soooo, I was trying to remember what prop I had so I know what I was starting with.