The exhaust system carries combustion gases away from the engine and out the back of the car. It also reduces noise, cleans emissions, and improves performance. It is a network of pipes, a muffler, a catalytic converter, and sometimes a resonator and exhaust manifold.

The exhaust manifold bolts to the engine and collects gases from each cylinder. It routes them into a single pipe, often through a turbocharger if the car has one. The gases then pass through the catalytic converter, which converts harmful pollutants into less harmful ones. Next comes the muffler, which uses chambers and baffles to cancel sound waves. Finally, the tailpipe releases the gases behind the car.

Exhaust systems are tuned for both flow and sound. A restrictive system reduces power. A free-flowing system increases power but can be loud. Manufacturers balance the two to meet noise regulations and customer expectations. Performance exhausts are a common aftermarket upgrade, though they may not pass emissions inspections.

Exhaust systems rust. Moisture from combustion condenses inside the pipes, especially on short trips. That is why mufflers and tailpipes often need replacement after 5 to 10 years. Stainless steel systems last longer but cost more. A leaky exhaust can let carbon monoxide into the cabin, which is dangerous. Any exhaust work should be done by a professional.