2019 Silverado/Sierra 1500 6.2L Atak 3.5in Diameter Polyphonic Harmonizer (BOR60680)Replace the small muffler behind the primary muffler in the Borla(r) S Type system with Polyphonic Harmonizer 60680 to attain the ATAK(r) sound level (louder than S Type). Borla(r) 'S Polyphonic Harmonizer Technology utilizes patented units that contain pipes of different diameters and lengths to create multiple exhaust notes that harmonize to deliver a clean, rich, full bodied sound to the Borla(r) mufflers. The mufflers then enhance this sound to