If we think of the engine as a glorified air pump then there needs to be an effective way to bring air into the pump and push it out again. This is achieved through the intake and exhaust systems. The intake begins with an air filter that is in charge of preventing contaminants from the outside environment from entering the engine and damaging the internal parts. In modern, computer controlled engines the intake is also fitted with various sensors that influence how much fuel is needed for the most efficient combustion. Without the exhaust system cars would be extremely loud and produce lots of pollution. The exhaust collectors, often called exhaust manifold or headers, channel the spent combustion gasses into one pipe where it is sent to the rear of the vehicle. This piping includes a device called a catalytic converter that is responsible for converting poisonous carbon monoxide into less harmful carbon dioxide. Further down the pipe is a muffler, which reduces much of the noise produced by the running engine.