The job of a Muffler is to muffle engine noises. Mufflers work by either absorbing or baffling sound. Rusted or road-damaged mufflers can actually leak and they should be replaced right away. You can actually customize your car’s sound with different mufflers so in addition to changing the look of your ride, you can also customize its sound!
For customizing the sound of your car you need to look for performance mufflers. These are the mufflers that work to actually amplify the sound, or change it in someway.