Absorption (packed mufflers) have a straight through design, they can have good flow but the packing begins to deteriorate and get louder as they wear out, and with modern engines the heat is very high which destroys the packing even quicker. Spin Tech's patented design provides maximum performance for today's modern engines. Its all done by means of a Spin sound trap, which captures sound vibration (noise) and turns it into heat within the muffler case.. As exhaust gases enter they are routed to the spin traps which create a high velocity vortex trapping the sound waves. The extremely high flow rates are achieved by a unique internal scavenging system that creates a venturi effect.