I am turning about 5000 rpm's with my 90 Johnson at wot on my 20 foot pontoon loaded down pretty heavy, with a 13 3/4 X 15p OMC prop. The boat is almost never loaded any heavier than it was on the test trip. I am figuring on going to a Solas 13 3/4 x 13p from iboats, but I see I can get a 13p 4...