You need to really work on balancing the load in your rig and getting your prop balanced and blueprinted will help as well, then seat time, seat time, and more seat time. Going to a 15in. jackplate will help your overall performance. I have the same set up, except I have a 15in. plate and a Hydro Tec 300 on mine, when it was stock, it would run 85-86 tourney loaded with 2 people.
08' 202 DC/ Yamaha 300 HDPI
Turbo Props Pro Staff