Re: Rpm
you will pick up about 200-250, have a better hole shot, but may loose a few MPH. if your turning 5000 at wot, your ok. the main thing about the proper wot rpm, is that a lower speeds you are not lugging the motor. you are fine in where you are. if you are skiing or pulling a tube, you will see a difference, on the take off, with the 15.
i wombat were posting at the same time, he gave good advice also.