On the Yamaha website. Pick the motor, select the boat, and they show actual performance figures for many boats, including mine.
Only problem was their link for this combination opened up data for another setup. I figured out their numbering scheme, and plugged in the appropriate http, and ended up with this unpublished link:
http://www.yamaha-motor.com/assets/p...3-46-TPH-C.pdf
Useful data. With 2 people, the best cruising speed, based on MPG, is about 27 MPH (4500 RPMs, 7.2 MPG).