I have a 2013 2275 RCW with Yamaha 150 and stainless steel prop. Most of the summer, I have been running around top speed of 32 MPH with around 5500 RPM. This past weekend, I had a little more weight on the boat, with a couple of heavier people. But I maxed out at 20 mph with a max RPM of 4750 RPM. I have less than 50 hours on this boat and motor. Any ideas?