Got 57 GPS today, first time out in 3 months (I am due for a tune-up). Have 21P Vengeance Prop. Tried the Mercury Prop Guide, which says for my setup to look at the 23P Laser II or Revolution 4, which might bring me over 60. Any thoughts? I have 4.3 MPI 1.62 ratio Alpha, WOT is 5000 (w/diverters engaged). My boat cruises beautifully at 3500 rpm, 45 mph, so don't want to jeopardize that handling...