I have a Hunter 356, 2003 model with 3GM30F AND MaxProp since new. I had it refurbished last year and changed from 22 to 20 degrees of pitch. I am going to change back to 22 when I pull next time as I went faster before I made change. PYI originally recommended 22 degrees and I discussed it with them before changing to 20. I can live with the change as I get my Max rated RPM of 3650 but my speed has dropped from 6.2 to 5.8 knots at my normal running RPM of 2750. I have more power but I'd rather have the cruising speed. I can get it, I just have to increase my RPM, but it is noisier and uses more fuel,when I do. If I go back to Florida, cruising a 10 hour day takes me 58 nautical miles versus my old 62. That 4 nautical miles takes me an extra 41 minutes so I think I am burning about the same total fuel just getting there slower and at a less percentage of total rated RPM. The power reduction is not worth the extra time spent and I don't need more power thru the water. Noise is barely different inside the saloon.
Get their recommendation at PYI. They know what they are doing and know what your boat should use as a setting.