DNA Motoring HFCHC01EX Stainless Steel Exhaust Performance Pipe Increases High Flow Air Rate and Maximizes Performance Dyno Proven Increases Low End Torque and Horse Powers; Instantly Gains up to 10 - 15 Hp. / Tq TIG Welded, CNC Machined Flange and Mandrel-Bent Piping / O2 Sensor Bung Insertion and Metal Gasket Included Inlet Size: 2.25" (Inner Piping Inlet Diameter; 3.00" Outer) / Outlet Size: 2.25" Professional Installer is Highly Recommended No Instruction Included