I have a 1998 nitro 896dc with a merc 200. it does not have a jackplate and i was goin to put one on it. what size do i need? it will only run about 60 loaded and i have tried 4 diff props and thats as fast as ive had it. i would like to get 65 out of it loaded. what could i expect to get out of the boat when i put one on?Thanks for help