aFe Power's Twisted Steel Race header for the Scion FR-S / Subaru BRZ / Toyota 86 produced a max gain of +10 horsepower and +13 ft. lbs. of torque verified by our in house dyno. aFe spent countless hours of R&D to develop the perfect balance of pure, race-inspired performance and sound with zero drone. These headers are constructed of near equal length mandrel-bent 1-5/8" 16-gauge, 304 stainless steel tubing and uses thick flanges for strength and to ensure a leak free seal. The smooth curves and increased diameter of this header helps remove restriction and keeps exhaust gas flowing smoothly for improved performance and durability. To eliminate dead space that can cause turbulence and hinder flow a 4-to-1 formed collector and optimized tube lengths are used to help increase exhaust velocity improving flow, torque and improve throttle response. This system retains factory mounting locations and requires no modification for a simple, hassle-free installation. TIG-Welded: 100% TIG-Welded by certified craftsmen for race proven strength and durability. TIG-Welding provides the strongest welds reducing stress cracks. Retains Factory Sensors: aFe has designed this system to retain all your factory sensors for a hassle free installation. Formed Collector: The 4-to-1 formed collector is used as an efficient way to collect header primary tubes together. 304 SS Construction: These headers are constructed of durable CNC mandrel bent brushed 304 stainless steel tubing for maximum performance, corrosion resistance, strength and resistance to cracking aFe headers are engineered and manufactured in our Corona, California manufacturing facility.