Replace the Polyphonic Harmonizer behind the primary muffler in the BORLA ATAK system with muffler 60679 to attain the S-Type sound level (quieter than ATAK). Built from premium T-304 stainless steel, superior to T-400 series knockoffs (such as 409), to give you the absolute best in performance and durability. Designed to provide maximum flow & power. Precision computer numerical control (CNC) manufacturing ensures an accurate fit. Best of all, BORLA stands behind every direct fit muffler with a Million-Mile Warranty. Just what youd expect from the worlds most experienced (and most winning) exhaust brand.