1) My boat seems to run the same speed (55 MPH) no matter if I have one person or five people in it, Do i need more prop?
2) Auminum, Merc?
3) 14.25"X21P
4) 4600-4800RPM, 55 MPH, loaded or unloaded
5) 350ci, Alpha MR (1.65:1 I think), 280ish Horse power
6) 1988 Rinker Capitiva 206, 20.5'...