The exhaust of every internal combustion engine used on any motorboat shall be muffled by an efficient muffling device or system which reasonably muffles the noise of the exhaust. The use of a cutout, bypass, or similar muffler elimination device, is prohibited, except when used by motorboats competing in a regatta, race, or other special event, or on trial runs and tuneups therefor, for which prior written authorization has first been obtained from the director of enterprise services.