There are generally three types of performance mufflers:
1. Reactive mufflers: This is the most basic type of muffler and is generally considered as restrictive mufflers. Reactive mufflers are excellent when it comes to noise reduction, but they generally fare poorly in terms of exhaust flow. The main goal in designing a reactive muffler is to minimize the number of restrictions by utilizing a set of internal tubes and sound chambers inside the muffler. Quality aftermarket reactive mufflers such as Corsa and Flowmaster utilize special chambers and delta plates to literally deform the sound waves created by the exhaust. The system will divide the exhaust flow and bring it back together to cancel out some of the noise frequencies.
2. Absorptive mufflers: If you are looking for a more aggressive exhaust sound, nothing comes close to an absorptive muffler. This type of muffler has been around since the 1950s and is popular with hot rodders and engine tuners. Absorptive mufflers have a straight-through design. The inside of the muffler has a perforated tube and contains a packing material that absorbs some of the unwanted sound (which causes that annoying droning sound in some units).
3. A combination of both reactive and absorptive: This type of muffler is considered by many to be the best in terms of reducing backpressure and producing a better sound. By combining the qualities of a reactive and absorptive muffler, the combination of two designs offers a better balance of sound and exhaust flow.
Generally speaking, the exhaust sound is correlated to the amount of power produced by the motor. A louder exhaust note means more power is retained by the motor, which can be unleased after stepping on the gas pedal.