Vehicle Code § 27150.1

No person engaged in a business that involves the selling of motor vehicle exhaust systems, or parts thereof, including, but not limited to, mufflers, shall offer for sale, sell, or install, a motor vehicle exhaust system, or part thereof, including, but not limited to, a muffler, unless it meets the regulations and standards applicable pursuant to this article. Motor vehicle exhaust systems or parts thereof include, but are not limited to, nonoriginal exhaust equipment.

A violation of this section is a misdemeanor.