Thank you so much for your involvement with the Owner's Club Forum! We hope you've gotten some great information and had the chance to interact with other owners on the current system.
I have a 2012 SD 187 with Yamaha 115. I bought it with an aluminum 13x17 prop and WOT is around 6400 rpms per the tach and around 30 mph top speed. I was worried about the rpms being too high and top speed being too low so I bought a 13x19 prop per the Yamaha prop selector tool. Did a test run with the new prop and WOT was only around 4800 and about 28 mph. Also with the new prop and adding 3 adults and 4 kids the boat would not get on plane. I also have smart tabs for reference. Why would going from a 17P to a 19P drop the rpms that much?