Re: can I make my 40 hp a 50?
Actually according the the hp rating rules of the NMMA, ( +/- 10% of the stated hp), your 40 hp could be 44 hp, and a 50 hp could actually be 45 hp. So the two motors off the showroom floor could actually be within 1 hp of each other.
Your best and least expensive option is to make sure the motor is running at its best, and propping it to hit the top of the rpm range. I would aim for 5300-5500 rpm.