Late in the season last year I purchased a 1988 Wellcraft 170 Classic open bow runabout. Boat came with a High Five, five blade prop. Research showed that prop was for V6 or V8 boats. Checked multiple prop selector sites and changed to 3 blade, 14.25x19 pitch Stiletto prop. Tuned boat up, (plugs, points, cap, rotor and wires). Timing and dwell set exactly to factory specs. First trip out this season, boat was slow out of the hole and could only get about 3600 rpm at WOT and 40 MPH by GPS. I'm more concerned with getting correct prop to be in proper WOT range than anything else. No skiers or tubers, mostly want a good all around prop. Boat ran great other than not getting to right RPM range. Lake was quite choppy that weekend but not to the point I feel would account for the poor performance. Should I stay @ the 14" diameter and drop to a 19 pitch? I think that much drop in pitch will get me in the range but I'm still learning about prop selection. Any help is greatly appreciated!