This resonator is designed to dampen the sound of our Cat-Back systems. Use ONLY with 140752, 140753 or 140758, or any of these with black tips. It does NOT fit competitors or Original Equipment systems. 3" diameter part. Built from premium, good quality T-304 austenitic stainless steel, superior to T-400 series knockoffs (such as 409), to give you the absolute best in performance and durability. Ultra-smooth mandrel bends ensure maximum flow & power, and precision computer-controlled CNC manufacturing ensures an accurate fit.