aFe's Twisted Steel long tube header and connection pipe deliver +24 HP and +27 lbs. x ft. torque over the factory. This system is constructed with 1-3/4" primary to 2-1/8" secondary, and 2-1/2" mandrel bent, 304 stainless steel, brush finished tubing for greater exhaust flow and longevity. 100% hand TIG-welded by certified craftsmen for proven durability. The long tube header incorporates a 6-2-1 Tri-Y designed. These features create a smooth transition to eliminate dead zones and improve flow. High quality band clamps and hardware to provide a quick, hassle-free installation. Performance Gains: +24 HP / +27 lbs. x ft. Torque max gains (Tested on a 2005 Nissan Patrol (Y61) I6-4.8L 4-Door Automatic). Tri-Y Design: Paired opposite firing cylinders with equal, specifically tuned primary lengths maximizes scavenging and increases torque throughout the power band. Stainless Steel Tubing & Laser Cut Header Flanges: High grade 304 stainless tubing with a uniform brushed finish provides a beautiful look and high resistance to corrosion. Laser cut 304 stainless steel header flanges provides superior sealing at the head surface. TIG-Welded: 100% TIG-Welded by certified craftsmen for race proven strength and durability. TIG-Welding provides the strongest welds reducing stress cracks. Factory Mounting Locations: 2-1/2" flanged connection pipe mounts directly to OE mounting location. Leak-Free Seal: High quality band clamps are used for a complete 360-degree sealing surface.