Aftermarket, Performance, and Add-on Parts
What's under the hood is important to air quality. Automotive emissions account for over 50 percent of all smog-forming pollutants in California. To improve air quality, the California Air Resources Board (CARB) requires vehicle manufacturers to develop engine and emission equipment systems that reduce the specific pollutants that cause California's severe air quality problem. These emission control systems are also required to be proven durable and reliable.
To ensure that these systems operate as designed, California Vehicle Code Section 27156 and the Federal Clean Air Act prohibit modifications that increase motor vehicle emissions. Since if properly designed, most performance modifications do not increase vehicle emissions, these same laws also allow the installation of parts or modifications proven by their manufacturers and the CARB not to increase vehicle emissions.