4-1 Race Header

The FSWERKS 4-1 Race Header is engineered for maximum exhaust flow and performance, specifically designed for track use on Duratec Focus models. Constructed from robust 16-gauge heavy-duty steel, this header features thick 3/8" laser-cut flanges, 1 7/8" mandrel-bent runners, and a 2 1/2" ID collector to ensure optimal exhaust gas velocity. It is finished with a polished ceramic coating rated for temperatures up to 1200° Fahrenheit, offering both aesthetic appeal and durability under high heat conditions. Installation is facilitated by the included oxygen sensor harness extenders, a 2-bolt gasket, and mounting hardware, requiring no welding. It is designed to provide a performance boost, with documented gains of 8-10 horsepower and 6-8 lbs. of torque at the wheels for lightly modified vehicles, with potential for greater gains on highly modified engines. **Important Considerations:** This product is strictly for RACE USE ONLY and is not street legal or intended for public roads. It is not for sale in California, and a release waiver must be completed and submitted with your order for shipment. A flex pipe is not included and may be necessary depending on the vehicle configuration. Fitment is confirmed for Ford Focus models with Duratec 2.0L (2005-2011) and 2.3L (2003-2007) engines, including the Focus ST Duratec 2.3L (2005-2007).