I just took delivery of a new 2017 16 foot with a 40hp Yamaha. I am now into my 3rd hour of break in. The prop is a 12,1/4 X 9 G. At YOT I can only hit 4800rpm 16 mph. I am looking for 6000rpm at YOT, and to operate at 5500rpm / 20mph. Any suggestions?