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Cycle Shack, Inc.’s Dealer Guide to California Emissions


Aftermarket Exhaust Sales


  1.  Aftermarket exhaust systems that can be sold legally 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 for use in “closed course competition use only” that have been adequately identified as such.
  1. In the case of exhaust systems for motorcycles, C.A.R.B.  considers aftermarket exhaust systems to be replacement parts if the following condition is met:  The vehicle was not originally equipped with a catalyst and all emission controls originally connected to the exhaust system are reconnected to the aftermarket exhaust system and are functioning properly; or

    a. The vehicle was originally equipped with one or more catalysts, but the catalyst(s) is retained and all emission controls originally connected to the exhaust system (e.g., an oxygen sensor) are reconnected to the aftermarket exhaust system and are functioning properly.  As long as they meet the above definition of “replacement parts,” “slip-on” mufflers are legal for use in California unless the muffler being replaced contained a catalyst.
  1. Executive Order Parts are aftermarket parts that C.A.R.B. has evaluated and determined do not adversely impact emissions, and thereby are granted an Executive Order (E.O.), which allows the part to be sold and used on specified motorcycles. Any aftermarket exhaust system that replaces or otherwise impacts emission control equipment, including catalytic converters, requires an E.O. to be sold and used on a motorcycle used on or off a public highway.

  2. Cycle Shack, Inc. has applied for AND received Six (6) C.A.R.B. Executive Orders (E.O.’s) after extensive compliance testing that cover various mufflers/exhaust systems for several Harley-Davidson Models & Years (E.O. #’s K-005, K-005-1, K-005-2, K-005-3, K-005-4, and K-005-5) which are Emission Legal (Compliant) modified and/or replacement parts that are legal to sell in California.  The Cycle Shack, Inc. product philosophy on our E.O. products is to put the catalysts back into the mufflers to keep catalyst heat away from the rider’s foot and leg.

    In the case of sale of slip-fit replacement mufflers (catalyst-back) the dealer must determine that the customer’s motorcycle has retained any O.E. Emission Control Components (such as O2 sensors and catalytic converters), so that the sale can be considered a “Cat-Back” replacement part (Emission Compliant) application/sale.


  1. Under the definition of “racing vehicle,” not being used on public highways isn’t necessarily sufficient; it also has to be used on “a competition vehicle.” The language describing a modified part intended for use on racing vehicles may read: “This product is legal for closed-course competition use only.”  C.A.R.B. can be expected to claim that a violation has occurred if a dealer installs a part intended for competition use only on a motorcycle that is ridden away from the dealership. It is also good practice for the dealer to require the retail purchasers of any parts intended for competition use only to sign a liability release/ indemnification statement to the effect that “I understand that this part is only legal for closed-course competition use”. 

Regarding Race Only Applications

Exhaust Systems for “closed course competition use only” may be sold under certain circumstances without California Air Resources Board (C.A.R.B.)    approval, BUT ARE PROHIBITED FROM USE ON PUBLIC HIGHWAYS, provided an adequate disclaimer is used in any advertising/packaging.  Cycle Shack, Inc., will also ask the dealer to sign a “closed course competition use only” release and indemnification agreement as part of such transactions.


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