California Code of Regulations
Title 13 - Motor Vehicles
Division 2 - Department of the California Highway Patrol
Chapter 1 - Licensed Stations and Muffler Installers
Article 1 - Licensed Muffler Certification Stations
Section 602 - General Requirements

(a) Performance Standards. Muffler certification stations shall maintain reputable business standards in the performance of work, and the premises shall be maintained in a clean and orderly condition.

(b) Measurement Areas. Sound level measurements for exhaust system noise certification shall be made only in areas meeting the requirements of this article.

(c) Personnel. The station owner or at least one full-time employee shall be knowledgeable of all regulations applicable to the licensing of muffler certification stations, exhaust noise certification limits, and exhaust system certification. If a station certifies exhaust systems by testing, the owner or employee shall be proficient in the calibration, use, and maintenance of noise measuring instruments. The licensee shall be accountable for the actions of his employees in installing and certifying exhaust systems and parts and shall be responsible for ensuring that untrained employees are not permitted to sign muffler certifications or clear enforcement documents. Trained personnel shall be capable of demonstrating their proficiency to departmental representatives whenever the station is inspected.

(d) Fleet Owner Station. Any station operated solely for servicing a licensee's fleet of 10 or more motor vehicles shall certify the exhaust systems or clear enforcement documents only on the fleet vehicles owned or operated by the licensee.