For Ford Mustang 4-1 Design 2-PC Stainless Steel Exhaust Header Kit - 4.6L V8 Precision machined steel flanges that provide a tight seal at the head and allows a high flow rate through the primary tubes Made From High Quality T304 Stainless Steel For Strength & Durability Constructed With TIG Welded CNC Machine Flange For Percision & Fitment All Tubing Is Mandrel-Bent Comes With O2 Sensor Insertion & Metal Gasket