I got a 1548 SS with a 1985 25hp Evinrude on it. I need a new prop. I found both 3 and 4 blade props. My current prop is a 13 pitch 3 blade. I was going to go to a 12 for a little more bottom end versus top speed. I have been told the 4 blade will do this by itself. So what better? 3 or 4 and if a 4 should I stay at 13 or drop to 12 with it as well? I do not know alot about this so I need help. Mostly run rivers and some lakes but I would not mind losing a little top end. My boat is supposed to run 28mph right now per the previous owner using GPS to track it. I would still like atleast 24-25mph. Also would the MPG's change dramatically running a different prop? Lets hear it from those that know a little more.