rmv 21818 OBX Performance Exhaust Header 03-08 Mazda 6 6cyl 3.0L Duratec Headers Precision CNC machined flanges with TIG and MIG welded construction Utilizes factory 02 sensor position Dyno Tested Track Proven To Increase Low End, High End Torque And Horse Power Value Added Direct Bolt On Set Up Without Any Modification Backed by OBX Limited Lifetime warranty from manufacturer defects