For GMC/Chevy 1500/2500 5-PC Stainless Steel Exhaust Header & Y-Pipe - GMT800 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