I have a 99 yami 90 on a 1750 (17 1/2 ft) vector hydra sports and it currently has a 19 pitch alum. prop that came with the motor when i bought it but i do not know the diameter for sure but i think its 13 1/4. Its to much i know because at full throttle trimed up high its only at 4000-4200 and it takes waaaay to long to get on a plane and seems to lose power after on a plane for a min or so. So what size would be better? is there a rpm gain rule of thumb per pitch number? like you get 500 rpm per number? So if i dropped to a 17 pitch would that put me at 5000-5200? I am a newbie so any and all info would be great! THANKS