Hi to everyone.I have a Ranieri Voyager 20 with Suzuki DF 175.With the 21X15Suzuki propeller i have 25kts in 4500 rpm and in wot (6100rpm) 38kts.I want to have 28-30 knts in about 4200rpm and 42knts in wot.What propeller i must put???? Thanks (and sorry for my English)