As far as speed, I have only gotten my boat up to a little more than 3/4 throttle and the speedometer read between 60-65, and that was PLENTY fast enough for me. Quoting Urban legend
I can assure you that boat does not do 65 mph with a stock 460 Ford in it. Not ripping your ride or your hobby of carting around half naked women...in fact I admire it. But realisticly that thing is not going 65 at 3/4 throttle.
Those speedometers, are basically junk. You need a GPS if you want anything close to actual. If you have a GPS and that thing does 65 mph at 3/4 thottle..... well then I will eat crow....and I prefer mine grilled