S.D. Codified Laws § 32-15-17
No person may drive a motor vehicle on a highway unless the motor vehicle is equipped with an exhaust system and a muffler both in good working condition and in constant operation to prevent excessive or unusual noise.
Exhaust systems on passenger or passenger-carrying vehicles used on any highway shall discharge the exhaust fumes at a location to the rear of the vehicle body or direct the exhaust fumes outward from the side of the vehicle body at a location rearward of any operable side windows. Any motor vehicle equipped with side exhaust according to the original vehicle manufacturer specifications is exempt from the location requirements. A bus used for the purpose of carrying school children may discharge the exhaust on the left side in front of the rear axle.
Exhaust systems on property-carrying vehicles used on any highway shall discharge the exhaust fumes at a point rearward of the passenger-carrying compartment.
No person may use a muffler cut-out on any motor vehicle upon a highway.
A violation of this section is a Class 2 misdemeanor.
SDCL 32-15-17