If an engine ran perfectly, the only byproducts floating around in its exhaust would be a bit of nitrogen, some carbon dioxide and water vapor. While combustion has been greatly improved since the days of the Ford Model-T, it has not yet reached that level of complete efficiency. As such, those puffs of fumes that shoot out of our tailpipes contain a noxious slurry of harmful elements, including carbon monoxide, hydrogen, unburned fuel, hydrocarbons, and traces of aldehydes, alcohols, ketones, phenols, acids, nitrogen oxides and carbon. Since these elements have the potential to wreak serious, irreparable havoc on the planet’s atmosphere, your factory-installed exhaust system is designed to filter out as many pollutants as possible.Because auto emissions affect us all, there are laws on the books that dictate just how much vaporized waste can roll out of your tailpipe. In order to ensure that cars, trucks, SUVs and vans are in compliance with these laws, they have to pass a smog test every couple of years. However, there is no single federal standard for acceptable emissions levels. Thanks to the Tenth Amendment of the constitution, each state in the USA has the authority to determine its own acceptable auto emission levels. What’s good in Wyoming may not fly in Delaware.

While there is no single smog canon, there is a sure fire test for performance exhaust manufacturers to know if their systems will be legal throughout the Union-does it pass in California? California is known for its rigid smog requirements. The California Air Resources Board (CARB) is a governor-appointed panel of scientists, lawyers and business men and women that sets the bar for emissions levels. California has the most ambitious emissions controls in the nation. Therefore, if an exhaust system can pass in California, it can pass anywhere else. When an exhaust system, or any performance part, claims to be “50 state street legal,” it means that the product has been tuned and tested to meet California’s strict smog requirements.

Some performance exhaust systems are designed for “off-road” use. This means that these particular systems are not designed to pass smog testing, and are not legal for street use. There are exceptions to the rules, though. In California, for example, any vehicle that is 30 make-years old or older is exempt from smog certification. Check with your state’s Department of Motor Vehicles (or its equivalent agency) for the laws of your land. When equipping an off-road auto, pick up an exhaust system by BD Diesel, Heartthrob, MBRP, Dynatech or Bully Dog.