My current height is 1 9/16" above the hull. Thats prop shaft dead center. According to the manufacturer there factory set up is 1 3/8's to 1 5/8's so i'm almost dead center. What kind of speed increase can i expect by raising them a bit and how high is to high ?

You may be able to run 1 7/8''-2'' won;t know till you try. I don't think any big speed gain possibly 1-2mph. Give it a try you have nothing to lose, watch the water pressure

you should probably have external water pickups for that boat for sure. Remember that just raising your X dimension for more speed is not always the way to go. You have to take into consideration the water conditions of where you will be running. I would think a hydraulic jack plate would be a smart decision. This is how races are won is having the right set up for the water conditions. Drive height, correct prop, etc. Is that 1-2mph gain in super flat water in which if you hit a wave the boat slows down 4-6 mph. Just food for thought.

thanks for the reply's.