DNA Motoring HDCNS02SER Exhaust Header Manifold [For 02-05 Nissan Sentra SE-R SPEC V B15 2.5L DOHC] Made From High Quality T304 Stainless Steel For Strength & Durability Constructed With TIG Welded CNC Machine Flange For Percision & Fitment 4-1 Racing Design Comes With O2 Sensor Bung Insertion & Metal Gasket Inlet/ Outlet: 2"/ 2.5"