Borla 2019 Chevrolet Silverado/Sierra 1500 6.2L Atak 3.5in Diameter Polyphonic HarmonizerReplace the small muffler behind the primary muffler in the BORLA S Type system with Polyphonic Harmonizer 60680 to attain the ATAK sound level (louder than S Type). BORLA'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 mufflers. The mufflers then enhance this sound to the character