I had a 15.5 X 17 on the Wellcraft and got like 36 mph at WOT 4400 rpms. Switched it to the one mentioned above and it put a little more pressure on my engine. Still original motor. I noticed a little oil leaking from somewhere around the timing cover so this more pitch put a little more backpressure in the crankcase is what I am thinking. I only ran it up to WOT to see what it would do coming back to the launch. I spent most of the ride around 3100 to 3200 trimmed up running. I have pulled this motor once to rebuild the front motor mount box and dont really want to pull it again but if I have to at least it is not a beast of a job.