Okay, I got my prop (14.25 x 22 4 blade Stiletto Stainless) and mounted it to my 1991 Evinrude 155hp commercial. It is running 4200 rpm at WOT. My question to the experts is should I drop to a 20 or an 18 pitch. I am told operatingrange is 4500-5500 rpm and the test was w/ 2 people and almost no...