I know there are motor series where the basic block and everything are the same between, let's say 90 and 130 HP, or maybe the 150 and 175 models. It's just the computer that controls the eventual output of the motor. I'm sure that's an overly simplified way to put it, but manufacturers do it for economy of scale. I've always tried to avoid getting the model which generates the max HP, just out of an abundance of caution. My JD tractor is the same way. One can get the exact same tractor frame with the same basic engine, but the addition of a turbo and some computer changes boost the output from 41 to around 57(?) hp.
Now, if one is boosting the HP to something that exceeds the Coast Guard rating for a given hull, then you are subject to running afoul of the law if something ever happens safety wise.