A dual exhaust system distributes a vehicle’s engine exhaust between two separate exit routes, usually ending in two separate mufflers. A single exhaust system sends all exhaust gasses through one exhaust path and muffler. If your engine has multiple cylinder banks (typical with six or more cylinders) and you have single exhaust, a “Y” pipe connects both cylinder manifolds to a shared exhaust pipe. From there, exhaust passes through one oxygen sensor, catalytic converter, and muffler. In a dual exhaust system, two exhaust pipes (usually connected to each other in an “X” or “H” pipe configuration) distribute the exhaust between two different sensors: the catalytic converter and muffler arrays. (Single mufflers with two intakes are also available.) With dual exhaust, your engine expels exhaust gas faster (using less energy) than with single exhaust. Most small-engine, non-turbo passenger vehicles come with single exhaust. Dual exhaust comes on certain vehicles featuring engines with six or more cylinders.