Iíd say the weight rating may be a structural issue.
However the max HP is almost always derived from a formula of beam and length I think, it is only very rarely actually tested for stability, itís a USCG formula I believe.
I would have no issue with exceeding max HP, but then I donít use full throttle except for getting on plane. Just as a point, at full throttle 5800 RPM
our dinghy with both of us in it or making 20 kts, back off 500 RPM
to 5300, and itís making 19 kts. So why run full throttle on this one?
Itís rated for 20 Hp and has a 20 Hp motor, that has a 6 Hp sticker on it
Hp formula and test method, testing is to my understanding very rarely done, and is almost always only done if a manufacturer is seeking a higher HP limit than the formula gives them.