Why is my VW Jetta so loud?
Over time a muffler will rust and develop holes and cracks. Eventually it will start to fail completely. A car that is running louder than normal is often due to a failing muffler. Other symptoms include a significant drop in gas mileage and an increase in exhaust fumes. Exhaust leaks – A hole in the exhaust system such as a muffler or exhaust pipe or a leak in places like the exhaust manifold can cause a significant increase in noise. Catalytic Converter Failure – One of the components for treating exhaust gases, a failing catalytic converter can lead to a louder engine.