I run a 19 pitch prop, loaded heavy and I get 30 mph (gps speed) @ 4,600 rpms. It will shift stiff if the idle is set too high, and if you are tied to the dock. I got a new shift interrupter switch for mine that mounts to the transom that is spring loaded to neutral so it puts some tension on the shift cable until it shifts into neutral. That helped alot. I did not hook the shift interrupter switch up. Idle needs to be set about 650 for it to shift. Mine has shifted like that from day one. with the merc 140 outdrive and sei outdrive, no difference. I have put about 400 hrs on mine in 9 years. 21' cheiftain, 1986 hull, engine/outdrive was a pre alpha 140hp (not original to the boat), now it has a 07 engine and 06 sei outdrive.