For Chevy/GMC Truck 5.0/5.7 w/o Air Injection Stainless Steel Racing Exhaust Header Application: 88-97 Chevy/ GMC Pickups/ SUVs without Air Injection (5.0L & 5.7L Only) Pair of 4-1 Design / 3-Bolt Flange / Bolts to OEM Y-Pipe 1.5" ID Inlet / 2.125" ID Outlet / O2 Sensor Bung Included on Driver Side TIG Welded CNC Machine Flange Increase High Flow Air, Instantly Gain 10 -15 Hp. / Tq.