An exhaust back box or rear silencer forms an integral part of car exhaust systems, despite this however they are not essential for a fully functional exhaust and as such it is not illegal to have it removed. Changing or removing your back box does not affect the emissions from your exhaust system as this is what a catalytic converter or dpf is for, whereas a car back box is for noise reduction only.

What is the purpose of a back box? 

This rear-end component functions to limit the sound produced by the gases that pass through the exhaust system. In addition to limiting noise, a back box also helps to slow down the movement of hot gases that travel via the exhaust system. You’ll find your car back box located at the end of the exhaust line, it is the most common muffler type found on cars.

When should I replace my back box?

In most cases when the full exhaust system has been kept in good standing the back box should last for 45,000 miles before it needs replacing. However, depending on how you drive and maintain your car, the back box can suffer from wear and tear much faster. For example, if you predominantly use your car for short trips around town or to local shops you’ll find that your car’s backbox won’t get hot regularly which is likely to lead to condensation, a common cause of corrosion. On the flip side to this, regular long journeys can lead to extreme temperatures in the back box which can cause damage and completely destroy other parts of the exhaust system such as the catalytic converter.  Another tell-tale sign is when parts rust through and the hangers-on the back box come off or when the back box breaks at the welds sometimes leading to the centre exhaust silencer also needing to be replaced.

Symptoms of a faulty back box?

  • Loud noises – if you notice loud noises coming from your exhaust particularly when speeding up it is likely your back box is damaged.
  • Cracks – are also a sign of a faulty back box, this will likely have been caused by corrosion.
  • Rust – leading on from the point above, also check for rust build up as this will lead to the corrosion of your exhaust system, which will lead to more severe issues.
What are the different types of backbox?

When replacing a car’s back box it is often the case that owners will opt for a performance back box or a rear silencer, and with a range of choices optimised for different makes and models at varying performance levels, exhaust back box prices can differ massively. Brands such as Scorpion and Akrapovic specialise in supplying parts for performance exhaust modifications with options ranging from fully-fledged systems to parts that slot right into your existing exhaust system. If you’re on the hunt for a new back box for your car check out the range of rear mufflers available on our website.