After the 2010 season of dealing with a performance problem with my 'Tower Of No Power' Supreme Marine finally figured it out.
It was a leak in the crankcase seal.
Test on Minnetonka 10/30 resulted in the following;
21P Stainless / 5400 RPM / 48 MPH - Now I can start playing with props
My recommendation to anyone having performance issues is to spray a little fogging oil on the seams
before spending alot of money on carb. & elec repairs.