Aftermarket Exhaust FAQ's

To all of our customers,

Our sales office in Chino has been receiving a lot of requests for information regarding compliance with state and federal regulations.

As a result we are making available a document prepared for our industry by the Motorcycle Industry Council (MIC). This document is intended to clarify proper use and sale of exhaust systems in the state as well as answers some frequently asked questions about this topic.


This is Motorcycle Industry Council’s interpretation of California law and regulations related to after-market exhaust systems. MIC has prepared this information in an effort to clarify related issues for dealers in California.


What exhaust systems and slip-on mufflers can a California dealer sell or install without violating California air pollution control requirements?

After-market exhaust systems that can legally be sold under California’s air pollution control requirements are (1) systems that are designated “replacement parts,” (2) systems considered “modified parts” for which an Executive Order has been issued, and (3) systems only for use on “racing vehicles” that have been adequately identified as such.


What exhaust systems and slip-on mufflers are considered “replacement parts”?

Under California Air Resources Board (CARB) regulations, “Replacement parts” are parts that have the same effect on emissions as the original equipment part that they are intended to replace. In the case of exhaust systems for motorcycles and ATVs, CARB considers after-market exhaust systems to be replacement parts if either of the following conditions is met:
1. The vehicle was not originally equipped with a catalyst and all emission controls originally connected to the exhaust system are reconnected to the after-market exhaust system and are functioning properly. (It is rare for other emission controls to be connected to a non-catalyst motorcycle or ATV exhaust system, but examples include an exhaust gas oxygen sensor or an air injection system.)
2. The vehicle was originally equipped with one or more catalysts, but the catalyst(s) are retained and all emission controls originally connected to the exhaust system (e.g., an oxygen sensor) are reconnected to the after-market exhaust system and are functioning properly.
As long as they meet the above definition of “replacement parts,” “slip-on” mufflers are legal for use on the road unless the muffler being replaced contained a catalyst.


Can I install an unapproved after-market exhaust system that was purchased by the owner from out of state?

Installation of unapproved after-market exhaust systems is legal only if the systems are “replacement parts” or being installed on a motorcycle or ATV for competition use only.

If there are any further questions or concerns, feel free to contact us at sales@yoshimura-rd.com or call (909) 628-4722.

You may also visit A.R.B.'s website at http://www.arb.ca.gov/ for additional information.

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Race series product restriction and affirmation


The RACE SERIES product you are purchasing removes, renders inoperative, or bypasses required elements of the emission control systems of EPA, certified motorcycles of motorcyle engines and may only be installed on motorcycles that are restricted to closed course competition. Installation of this product on a motorcyle that is ridden on a public street, highway, or public lands violates the tampering and defeat device provisions of the Clean Air Act & 203(a)(3)(A) and/or & 203(a)(3)(B) and may subject you to a civil penalty of up to $37,000.

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  3. that any motorcycle on which I install the RACE SERIES product will be restricted to closed course competition and will not be ridden on any public street, highway or public lands.