What BD said. I would run away from any dealer that is willing to put more HP on the boat than the CG recommends. I don't know if it is illegal, but it sure sounds like a bad idea.

If you want more speed, get a boat designed to go faster. The Arima will still pound in a chop regardless of how much HP you have, and in fact the heavier motor will pull the stern down more, exacerbating the bumpy ride. You can install oversize trim tabs, but then you are putting the extra HP into the tabs, not MPH. It is very difficult to overcome basic hull design points with add-ons.