took my old 13x17 prop to the repair shop and they said it had 3" worn off the blades. it ran my 90hp yamaha at 5500rpm, the motors range is 45-5500, so i was just right. the new one is a 13.25x17, and, with so much more material runs the boat at 4800rpm. thats still in the range of my motor, but since i want to be in the high end of the recomended range should i go with a 15 pitch? the old prop was the original from the factory i belive. it runs so much better with the new one and i went from 34.5 mph to 38.5 mph (gps). with a 15p prop that will get me higher rpm's will i see more mph?