Leroy Engineering Emissions Statement



Motor vehicle emissions standards are intended to help achieve and maintain air quality goals that benefit human health and the environment. U.S. federal and state and Canadian law prohibits knowingly removing, modifying, or making inoperative, or causing someone to remove or render inoperative, or otherwise tampering with, any part or element of design installed in compliance with motor vehicle emission standards on a motor vehicle or nonroad vehicle, or otherwise modifying any required emission and noise control systems. The emissions-related Leroy Engineering Parts listed on this website identified as competition use only and should not be installed or otherwise used or operated in vehicles that are:

(1) “motor vehicles” used on public roads, streets or highways at any time; or

(2) off-road vehicles, unless used exclusively for competition motorsports.

U.S. federal and state and Canadian provincial agencies have the authority to impose substantial civil and criminal penalties against individuals and companies that do not comply with these laws. Leroy Engineering customers are responsible for ensuring their use of Leroy Engineering parts complies with applicable federal, state/provincial and local laws, regulations and ordinances, and for ensuring that modified vehicles are operated in a manner that complies with applicable laws. In an effort to help customers comply with emissions laws, the product descriptions for many parts include emissions-related warnings and notices. This page summarizes the emissions-related information that you may see on this website.


The Leroy Engineering Catalog includes parts that are intended exclusively for use in competition vehicles that will be driven only on a racetrack or off-road course and not on public roads, streets, or highways. By “competition vehicles,” Leroy Engineering means vehicles used exclusively for competitions organized and sanctioned by a local or private body and conducted on a closed circuit or other non-public road. Customers should not install parts accompanied by this warning on vehicles that will be driven on public roads, streets, or highways, as those parts are not designed, tested, or certified for that purpose. The product descriptions for such parts are accompanied by the following warning: 


Because of their effect on a vehicle’s emissions performance, certain parts in the Leroy Engineering Catalog are intended exclusively for use in competition vehicles. This designation means a part is designed and intended for use in vehicles operated exclusively for competition: in racing or organized competition on courses separate from public streets, roads, or highways. Installation or use of this part on a vehicle operated on public streets, roads or highways is likely to violate U.S., Canadian, and state and provincial laws and regulations relating to motor vehicle emissions.


Manufacturers of add-on and modified emissions-related parts (aftermarket parts) that sell their product for use in California vehicles must obtain an exemption from the California Air Resources Board (CARB). This exemption is called an Executive Order (EO) and allows the part or modification to be installed on specific emission-controlled engines, vehicles, or equipment.  An EO is granted if the product has been determined not to reduce the effectiveness of required motor vehicle or off-highway motor vehicle pollution control devices or result in emissions levels that do not comply with existing state or federal standards for the same vehicle model year for which the part is approved, nor otherwise cause engines, vehicles, or equipment to be noncompliant with the vehicle emissions certification and anti-tampering laws.

Every aftermarket part that has been exempted by CARB is assigned an EO number and is subject to installation and use restrictions. The EO number will appear on a special exemption label affixed to the part or its packaging.  Consumers are advised to familiarize themselves with the EO and its limitations and restrictions to ensure that such parts are installed and used properly. 

50 State legal means that this part has undergone an evaluation by the California Air Resources Board (CARB) and that CARB has determined that the part or modification has been shown to not increase emissions in violation of applicable standards when installed and used properly in the vehicle application(s) identified in the product description and EO. CARB policy authorizes consumers to install and use these parts in specified vehicles driven on public streets and highways. Emissions-related parts that have an EO list the EO number that can be used to locate the installation and use restrictions of

that part on CARB’s website: https://ww3.arb.ca.gov/msprog/aftermkt/devices/amquery.php.   


Some of the parts listed on this website are intended only for use in racing, track applications or “off-road” vehicles—they are not intended for use on public roads. U.S. federal law and Canadian law prohibit an automobile manufacturer or dealer from removing, modifying or rendering inoperative any part installed in compliance with an applicable Federal Motor Vehicle Safety Standard on a motor vehicle used on public roads.

Many parts intended for use on private property, including racing on a track, are not designed or tested for crashworthiness or to meet safety standards applicable to public-road use, and may adversely affect the original intended performance or handling characteristics of the vehicle. These parts are designed and intended to be used with experts supervising their installation and use, to help assure the proper and safe operation of the vehicle.

Vehicles equipped with Leroy Engineering parts also may not meet U.S. federal, state, or local emission laws, regulations, or ordinances, and may not be operated on public roads, streets, or highways or for non-competition purposes. Further, the federal government and many states and provinces have enacted laws with various penalties for tampering with or otherwise modifying any required emission or noise control system. Leroy Engineering customers are responsible for ensuring their use of Leroy Engineering parts complies with applicable federal, state and local laws, regulations and ordinances.

At this time, exemptions are made in Ohio and some other states for off-road/race-only competition vehicles used only in sanctioned racing applications such as the SCCA. Leroy Engineering won't modify vehicles that are used in states that do not have a similar exemption.

Rule 3745-80-02 - Ohio Administrative Code | Ohio Laws

Competition only vehicles are those that have had modifications made to their emission system and thus are unregistered and trailered to sanctioned race events. It hurts our race industry when people put their race cars on the road knowingly violating EPA federal laws.

Before we perform any work on any competition only vehicle, we require the Leroy Engineering Emissions Statement Acknowledgement Form to be signed to ensure that the vehicle is not registered in any state.

Leroy Engineering Emissions Statement Acknowledgement Form


Additional information regarding the EPA Clean Air Act regulations can be found at the following links:

Clean Air Act Vehicle and Engine Enforcement Case Resolutions | US EPA

Recognizing the Protection of Motorsports Act (RPM Act) | Specialty Equipment Market Association (SEMA)

Correction: Warning of EPA racecar threat, SEMA urges industry to campaign for RPM Act | Repairer Driven News

Fight for Your Right to Race! EPA Race Car Ban 2020 Update | Hot Rod

EPA "Engine Switching" policy | Grassroots Motorsports Forum

Edelbrock Product Emissions Guide | Edelbrock

Conditions of Use | DIYAutoTune.com

Repair of Exhaust and Emission FAQs | Ohio EPA

Gear Box Z, Inc., Clean Air Act Settlement | US EPA

More Than a Million Car Enthusiasts Are Taking on the EPA | MotorTrend


Leroy Engineering is committed to performance parts development that allows enthusiasts to modify their vehicles and remain compliant with emissions requirements. The information provided here is intended to provide general guidance of interest to most consumers, and may not apply to all vehicles or all situations.