Question on Prop size

[chumbucket]

What are you currently getting for top end RPM's with that prop? Sounds like it should be close. Ideally, you should be withing the mfg top end specs (typically between 5000-5500 or there abouts). You don't want to go too much over (not working the motor enough) or too much under (working the motor too much).
So, that being said, You are the one that needs to determine wether or not your boat is propped correctly or not. Load the boat up as you would normally do for a day on the water, then do a test run to see what your top RPM's are. Then you can make adjustments to the pitch accordingly. An increase in prop pitch (say from 19 to 20) will decrease your RPM's by about 200. Conversely, a decrease in pitch will raise your RPM's by 200 for every pitch size. ;)