For those of you who purchased a BORLA S - Type system, PN 140791 or 140791BC and want to step it up to the ATAK sound, replace the front resonators with this set. Each resonator is built from premium T - 304 stainless steel, superior to T - 400 series knockoffs (such as 409) to give you the best in performance and duarbility. Ultra - smooth mandrel bends ensure maximum flow power, and precision computer numerical control (CNC) manufacturing ensures an accurate fit. As with all BORLA products, it is covered by the famous Million Mile Warranty.