Exhaust system to open air — everything from the header back. Header-back systems are generally produced as aftermarket performance systems for cars without turbochargers. The Turbo-back (or turbo back) is the part of the exhaust system from the outlet of a turbocharger to the final vent to open air. Turbo-back systems are generally produced as aftermarket performance systems for cars with turbochargers. Some turbo-back (and header-back) systems replace stock catalytic converters with others having less flow restriction. Some systems (including in former time all systems) (sometimes nowadays called catless or de-cat) eliminate the catalytic converter. It is illegal and is against Federal
Defeat device Defeat device A defeat device is any motor vehicle hardware, software, or design that interferes with or disables emissions controls under real-world driving conditions, even if the vehicle passes formal emissions testing. The term appears in the US Clean Air Act and European Union regulations, to describe anything that prevents an emissions control system from working, and applies as well to power plants or other air pollution sources, as to automobiles. The United States Environmental Protection Agency (EPA) has taken numerous enforcement actions against car makers and other companies that have used or installed defeat devices, whether deliberately, or through