Namely, it replaces the rear axle-back and tips and then a portion of what we refer to as the mid-pipes. This system is emissions friendly and doesn’t require any tuning. In New Jersey, vehicles must pass emissions testing to ensure they meet environmental standards. Since cat-back exhaust systems do not modify the catalytic converter or engine management system, they generally do not affect a vehicle’s ability to pass emissions testing.

Most designs of the time therefore included secondary air injection, which injected air into the exhaust stream. This increased the available oxygen, allowing the catalyst to function as intended. Cat-back exhaust systems replace every component behind the catalytic converter, including most piping, mufflers, resonators, and tailpipes.

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