The exhaust of every internal combustion engine used on any motorboat shall be effectively muffled by an efficient muffling device or system used as to muffle the noise of the exhaust in a reasonable manner. The use of cut-outs is prohibited, except for motorboats competing in a regatta or boat race approved as provided in § 69121 of this Chapter, and for such motorboats while on trial runs, during a period not to exceed forty-eight (48) hours immediately preceding such regatta or race and for such motorboats while competing in official trials for speed records during a period not to exceed forty-eight (48) hours immediately following such regatta or race. SOURCE: GC § 8995.16, as renumbered by P.L. 15-54.