I have a standard aluminum prop for my 115 yamaha and wanted to go to stainless steel because my lake has some debries. Right now it's a 13 1/2 x 15 should I stay they same pitch? I have a 21 slx with the sps package if that makes any difference. I was looking at solas props but can't seem to figure out which size I should go to. Right now I hit 32 mph but top end isn't as big of a deal want little bit more acceleration for tubing and skiing so should i go with a cupped prop? Any help would be greatly appreciated.