ThunderMax Emissions Notice For California A.R.B Compliant Vehicles

ThunderMax makes every effort to accurately label “Competition Use Only / Race Ready” products intended for use on closed course competition motorcycles only; differentiating them from “Highway / Street-Approved”, everyday use products.

Use of select racing products, which may not be emissions-compliant, on highway motorcycles is subject to California Air Resources Board (CARB) regulations and could be considered tampering with your vehicle’s ability to meet emissions standards. California’s anti-tampering law, Vehicle Code Section 27156 (VC 27156), prohibits the installation of any add-on or modified emission-related part of any pollution-controlled motorcycle, unless the part has been exempted by ARB. Ultimately, it is the purchaser’s responsibility to determine suitability of parts for their motorcycle application and ensure compliance with ARB emissions regulations.

California Air Resources Board (CARB) regulates motorcycle aftermarket parts that have the potential to impact emissions (Aftermarket Critical Emission Control Parts). In most cases, the sale and use of emissions related aftermarket parts on motorcycles is prohibited unless it is either a "Replacement Part" as defined by California, or is a specifically authorized use of that part as reflected in an Executive Order and labeled as an "EO Part". These CARB regulations essentially place all emissions related aftermarket parts into three categories:

(1) Replacement Parts

Replacement Parts are aftermarket parts that ARB considers to be functionally equivalent to the stock part they are intended to replace, and therefore would not impact the emissions (exhaust, evaporative, or both) from these vehicles. These parts are appropriate for sale and use on motorcycles used on or off the public highways.

(2) Executive Order Parts

Executive Order Parts are aftermarket parts that ARB has evaluated and determined do not adversely impact emissions, and thereby are granted an Executive Order (EO), which allows the part to be sold and used on specified motorcycles (exemption from the prohibitions in VC 27156 and 38391). Any aftermarket critical emission control part (including exhaust systems, ECU, and oxygen sensors) that replaces or otherwise impacts emission control equipment, including catalytic converters, requires an EO to be sold and used on a motorcycle used on or off a public highway.

Aftermarket part manufacturers are required to provide a label to identify each exempted part sold. The label indicate’s the manufacturer’s name, device name, and valid E.O. number assigned by ARB. The format of the E.O. number is D-XXX-XXX, where “XXX” is a series of designated numbers. The label is either affixed directly to the part itself or included with the part with instructions to install if in a visible location. Remember to always look for this label when shopping for emission-related aftermarket motorcycle parts.

A listing of exempted motorcycle critical emission control parts in compliance with applicable California evaluation procedures can be found here .

(3) Competition Use Only Parts

Competition Use Only Parts may not be sold or used on a motorcycle that is used on or off the public highways other than those motorcycles used exclusively for competition. Competition Use Only Parts are aftermarket parts that replace or otherwise interfere with the operation of an emission control device, such as an catalytic converter or oxygen sensor, and may be sold and used on a motorcycle that is used only for closed course competition.

If there are any questions or concerns, please feel free to contact us at You may also visit ARB’s website for additional information.

For California riders, ThunderMax offers ECU units (“ThunderMax 50”) for select motorcycle models which are in compliance with applicable CARB evaluation procedures and are considered Executive Order Parts. These units have been labeled with appropriate E.O. fixed to the ECU housing and a Complete Listing of Available ThunderMax 50 Units Can Be Found Here. All other ThunderMax EFI units are considered Competition Use Only / Race Ready are NOT LEGAL for street or highway use in California.

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