Function

• Twin loop mufflers force the pulses through the muffler twice, reducing the sound produced. Some twin loop mufflers also use absorption to dampen the sound but that feature varies with brand.
  
  

Length

• The pipe length helps it behave as if it were tuned, like a brass wind instrument, helping it cancel specific ranges of sound. Twin mufflers produce different sounds based on pipe length. Those with short tubes have a higher pitched sound while those with long tubes sound deeper.
  
  

Effects

• The twin loop design helps reduce the noise emitted by the muffler without cutting engine performance. This is more effective than using a silencer on the muffler since silencers function by cutting exhaust flow through the muffler.
  
  

Horsepower

• The impact on the engine's overall power varies with the type of twin loop muffler installed. Some produce a negligible effect on the vehicle's motor, while others can boost horsepower by up to 10 percent.