Ok first for the boat info: 94 Glastron 17" SSV 175 with 3.0 Mercruiser 115HP currently the prop is brand new a 3 blade 13.75 x 21 (what it says on the prop). Well Im fixing to be adding a Big Air tower to the boat and want more low end pull to help out the wakeboarding situation. I could care less about top speed just want more low end. From what Ive gathered I think a 19 pitch 4 blade would do the trick, but what size? Any suggestions/recommendations are appreciated. Thanks - Josh