Are Random Turbo And Supercharger Kits Road Legal In The USA?

Are They Road Legal?👈

A Garrett GTX5533R Gen II Turbocharger 

In the United States, installing aftermarket turbocharger or supercharger kits isn't inherently illegal, but their road legality hinges on strict emissions regulations, particularly those set by the California Air Resources Board (CARB) and the Environmental Protection Agency (EPA). These agencies enforce standards that ensure vehicle modifications do not increase harmful emissions. Whether or not a forced induction kit is street-legal depends on whether it complies with these emissions requirements. Simply put, a high-performance kit without proper certification might dramatically improve power, but it could render your vehicle illegal to drive on public roads.

CARB plays a central role in determining emissions legality in California and many other states that have adopted its standards. To be legal in CARB states, an aftermarket turbo or supercharger must carry a CARB Executive Order (EO) number. This number certifies that the product has passed emissions testing and does not interfere with emissions-control systems like the catalytic converter or EGR valve. A CARB-exempt kit is usually sold with documentation or a sticker verifying its EO number, and it's the only way to pass a smog inspection in California and over a dozen other CARB-aligned states.

A 1ZZ-FE TRD Supercharger And Pully

Outside of CARB states, the rules vary. Some states defer to the federal EPA standards, which are typically less strict, while others have minimal or no emissions inspections at all. In states with limited testing, many enthusiasts install non-certified kits without legal issues, especially if the car still passes an OBD2 readiness check and shows no engine lights. However, this is a legal gray area. A kit may pass functional inspection but still be technically illegal if it alters or removes emissions equipment. It’s important to understand that legality doesn’t always align with a car's actual emissions output, compliance depends on having the right paperwork and certification.

A Rotrex Supercharger Kit

Random or “universal” turbo kits from sites like eBay or lesser-known vendors rarely meet emissions standards. These kits often lack proper tuning support and emissions testing, and almost never come with a CARB EO number. Using them in CARB states is a guaranteed fail on smog tests and could also draw attention from law enforcement, potentially leading to fines or a referee inspection. Even in more lenient states, using uncertified kits can still cause problems if your vehicle is selected for random inspection or resale.

A TRD CARB Sticker

There are, however, several supercharger and turbocharger kits on the market that are emissions-certified and therefore legal to use on public roads. Brands like Jackson Racing, Edelbrock, and TRD have developed forced induction systems with full CARB approval, designed specifically for popular platforms like the Honda Civic, Toyota 86, and Ford Mustang. These kits tend to be more expensive because of the added cost of compliance testing, but they offer peace of mind for those wanting performance upgrades without legal risk. Before purchasing any kit, you should always verify whether it has a CARB EO number by checking the manufacturer’s site or searching the CARB database.

In conclusion, while aftermarket turbo and supercharger kits can be road legal in the U.S., legality depends entirely on whether the kit has been certified for emissions compliance. If you live in a CARB state, only a kit with a CARB EO number will be street-legal. In other states, you may have more leeway, but uncertified kits still pose risks. For anyone considering forced induction, it’s critical to balance performance goals with legal responsibilities, doing your homework beforehand can save you thousands in fines, failed inspections, or forced removal of parts down the road.