I just bought a 1995 18" Chris Craft with a 4.3 Cobra. On my initial test ride, the fastest I could get out of boat was 35MPH (GPS) and 4000 RPM with 6 average size people and about 12 gallons of gas. The service manual says that optimum RPM is 4200-4600. I have a SS Ballistic (346032) prop that...