RPMs don't get associated with any particular boat. For any given boat/motor/prop combination, the proper prop should be selected. The rig should be propped so that the engine runs just at the maximum engine-manufacturer approved RPMs. Generally speaking, if the pitch of a prop is too low for a boat, the engine will over-rev the RPMs and the rev-limiter will kick in. For a prop with pitch too high, the engine will bog down and never achieve the power rating intended by the manufacturer. That power level depends on reaching the max RPM.
I don't know what the max RPM is for your particular engine, but most SHO's state 5000-6000 RPM as the max power range, so you appear to be WAY out of line at 4000 RPM. You are either grossly mis-propped, have an improper engine height, or a mechanical issue. The proper prop on that boat should allow a 250 SHO to run 5000+ RPM.