What do Catalytic Converters Do?
Catalytic converters clean bad gasses and unburnt fuel out of the exhaust to help clean the air. They convert carbon monoxide, nitrogen oxides, and unburnt fuel to less harmful molecules.
Catalytic converters were first produced in 1973 at the Englehard Corporation and began being used widespread around 1975. High emission places like Los Angeles were experiencing smog and haze from harmful gasses in vehicle exhaust. With the reduction of the gasses letting out of the exhaust, Los Angeles and other cities were able to clean up their air quality.
Why Do I Need to Put a Catalytic Converter Back On?
The Clean Air Act Amendment, a federal law that went into effect in 1990, restricted private car owners from removing or installing catalytic converter delete pipes for their vehicles. Before that amendment, only companies or businesses could not remove or delete catalytic converters but private owners could. This 1990 amendment greatly affected people working on their vehicles.
You can view the link to the Environmental Protection Agency (EPA) regulation here: Clean Air Act
No matter what your stance is on the converter law, removing a catalytic converter for sound or performance is illegal in every state in the United States! They do make a large difference in air quality and will forever be a part of vehicles powered by internal combustion engines.