Mercury Outboard Props and prop question

So on my 2001 90 hp fourstroke there is a sticker on top of the cavitation plate with a ’14’ on it. Does this mean a 14″ diameter prop is the biggest it can have? Looked at some other mercs and saw the same sticker with varying numbers on them.

Also in regards to props, I know the rule of thumb for prop pitch and its relation to max RPM’s, but does the diameter also play a role? After running the lund for a week up at Kab. I was very impressed with it overall, but I noticed with some tweaking on the prop I could probably get even better performance. Has a 13x19P on it now, but a bit slow to get on plane with more than just me in it and I was only getting up to 4600-4700 RPM’s with the throttle to the floor. In theory going down to a 13.75×15 prop should give me, by pitch, another 600-800 RPM, which would put me right into that 5300-5500 WOT RPMS and a lot more hole shot, but does the extra .75″ diameter play a role too?

Lastly, the motor is pushing a 1600 lund pro sport and my wife and I are both not small people, would there be any advantage to testing out a 4 blade?

Thanks for the help guys, trying to narrow down the choices.

Im not sure what the sticker means but I can tell you a 4 blade prop made a huge difference in my application! I have a 115 opti on a 17.5′ deep v with a full windshield. I think it had a 21p 3 blade and was way over propped when I bought it. Didn’t know much about propping so just put a hydrofoil on it and let it be for a few years. After doing some reading I decided to try some props that were suggested by the local prop shop. Did some more reading and settled on the quicksilver nemesis in a 4 blade 19p, its still an all aluminum prop. They ordered it in for me and were willing to let me return it if i didn’t like it. It has a much better hole shot, better slower speed to keep on plane, better hold out while making corners, and added almost 4 mph to my top speed! Went from 38-39 to 42-43 mph. They have a smaller diameter for less flex, but with the 4th blade they push more water. I would suggest finding a local prop shop or marine dealer that will allow you to borrow or at least purchase and return props until you find one that works. Find the right pitch prop that puts you in your recommended max rpm and play with different types and brands until you find one that suits your needs. Good luck!