S.C. Code Ann. § 50-25-1110: Noise control requirements.

Any motorboat operating upon waters on Lake Wylie shall comply with the following noise control requirements:

(1) Motorboats with inboard-outboard propulsion machinery shall exhaust through the propeller.

(2) Inboard motorboats with "V"—drives—jets or propeller propulsion machinery with exhaust through the transom shall be water cooled with a steady stream of water or exhaust underwater while under way or exhaust through an automotive type sealed (baffle) muffler for each exhaust stack, with exhaust openings not to exceed two inches in diameter. Boats with original propulsion machinery made before 1970 are exempt from the requirements of this item.

(3) Motorboats and their propulsion machinery which exhaust over the transom shall exhaust through an automotive sealed (baffle) type muffler for each exhaust stack, with exhaust openings not to exceed two inches in diameter. Glass pack mufflers, resonators and above water open exhausts are prohibited for such motorboats. Baffle inserts are prohibited on all inboard boats.

(4) Motorboats with outboard propulsion machinery shall exhaust under water at all times unless designed or modified to exhaust above water and comply with the provisions of item (3) of this section.