When I bought my 17' Alum boat from BPS back in 2003, it was rated for a 115HP but BPS only would put a 90HP on it. The guy that sold me the boat said that BPS does not max out the HP on aluminum boats due to safety reasons. I could have taken the hull elsewhere and had it rigged with a 115HP if I wanted to but BPS would not do it. Consider the Safety aspect more than the legality aspect in your motor choice. Saving a few $$$$$ or getting a good deal on a motor will be no good to you if the hull can't take the additional HP, especially an older hull. Even with my 90HP motor I have had several cracks in the metal - no where near a center beam or joint even though it is an All Weld Hull, and I think it is due to the high waves at Ky Lake and the fact the boat will still flex more than a Fiberglass Boat.