I can tell you that my 2000 225 Tournament with a 2000 225 OX66 got an honest 2.5 mpg at 4000 rpm which was 28-29 mph. I had an EP-60 hooked up to the Simrad. I can also tell you that I got 1.5 at 5400 RPM and 42 mph.
I would think 2.5-2.75 for a 4 stroke is probably pretty close. You might...