Most motorists take the exhaust system fitted to their car for granted - it's hardly visible, doesn't have any moving parts and doesn't require maintenance other than inspection. But the exhaust is part of a vital, complex and scientifically designed system, designed to do much more than simply quieten the sound coming from the power unit; an efficient exhaust system improves power output, decreases fuel consumption, protects the environment and minimises engine noise.

Often motorists are unaware of their exhaust system until it fails - either a hole has developed in a silencer box or a mounting fails and part of the system drags along the road.

Every engine has a specially designed, tailor-made exhaust system specifically created to maximise the engine's power through efficient management of exhaust gasses. The red hot gasses are directed from the exhaust ducts on the engine's cylinder head, through the manifold and down into the exhaust pipe. There the gasses pass through a series of silencer boxes, where vertical plates called baffles (perforated tubes and basalt wool) control the gasses and reduce the noise before expelling the gas through the tail pipe.

With car manufacturers and exhaust system designers becoming increasingly concerned about environmental issues, a new component is becoming increasingly common in the exhaust system; the catalytic converter. This component - known as a 'CAT' - is designed to drastically reduce the environmentally hazardous content of the exhaust gasses. Using a ceramic-based filter, the noxious elements are converted to relatively harmless gasses before passing their way through the system.

When an internal combustion engine starts, especially from cold, significant amounts of water and corrosive chemicals are produced as a by-product of combustion. You will often see drops of water dripping from the exhaust tail pipe of a car that has just been started from cold. Unfortunately, these corrosive elements gather in the silencer boxes and attack the metal from the inside, so a silencer might look in reasonable condition from the outside but could be perilously close to failing.