The rear muffler determines the sound and the appearance of the outlet. It offers the best balance between what you spend and what you hear: at the same diameter, the body volume and baffle design distinguish a deep tone from an unpleasant resonance at 2,500 rpm on the motorway.

Keeping a centre muffler cancels out that resonance. Removing it makes the car louder everywhere, including where you did not want it - this is the most common regret after an exhaust modification.