i have 25 hp johnson on my 1992 tracker. its 16 foot and is rated for a 60 HP. the prop on the 25 is currently a 3 blade 15p. i run about 25mph with me in boat (250lb)..and batterys and gas...equipment etc. i would love to upgrade to a 60 but money is short as of now. Wondering if a 4 bladed 15p prop would give me more speed...