You should be able to turn more rpms then that I would think, although I have a Yama 4 stroke like I said earlier I have mine set right now at about 4.25" below the pad with a yamaha pro 21 pitch running 5800 rpms at 49-50 mph. I'm in no ways a speed freak, but more or less I just want what I own to work as intended. It seems like your in the right road if your trying to get everything out of it though. Usually you can find a good second hand jackplate online, it took me many tries to get my boat to where it is now. It's just the headach of fine adjustments, test, adjustments, test, etc..... the only other thing is to getting used to driving with the trim, up and down in turns so you don't catch air when turning.