The exhaust manifold found on the 2002-2006 Nissan Altima DOHC 4 Cylinder Engine were designed to combine the exhaust gasses from each of the cylinders quickly with a manifold that was cost effective to produce. Our 4-1 off-road racing headers are designed to allow the exhaust gasses to flow more freely from each cylinder and combine in a more efficient manner. Tubing has been optimized for the 2.5L engine. This creates a reduction in cylinder backpressure and improved exhaust gas velocity. These improvements free up lost horsepower and torque. An added benefit is a more performance oriented exhaust sound.
Inlet: 2"x1.25" (Rectangular) / Outlet: 2.5" Made of High Quality T304 Stainless Steel for Strength & Durability Constructed with TIG Welded CNC Machine Flange for Percision & Fitment Comes with O2 Sensor Bung Insertion & Metal GasketThis product is compatible with: Nissan Altima 2.5L QR25DE I4 (2002-06)