Numbers for a 20 I/O

[Briguy]

Steve, If you are only topping out at 3250 you are lugging the engine. We need more information and you need to do more research. How is your holeshot? (no jokes here) What is your cruise rpm? Why the 4 blade prop? What is the HP of the motor and what is the manufactures wot rpm range? Is your bottom clean? (again, being serious) Is your prop in good shape? What is the gear ratio in your lower unit? All of these factors come into play when deciding what prop to use. 3250 rpm's is way too low unless you have a diesel. In my best guess you should be turning 3000 at cruise and 4200-4600 at wot with a full load. Talk to your dealer.