Megan racing headers are made with T-304 stainless steel, mandrel bent tubing, and CNC machined flanges. Each set is tested and dynoed to make sure the fitment and performance meet our goal. Each header comes with 1 year warranty. Specs are as follows: Fits 03+ EVO VIII, T-304 stainless steel with polished finish, 1.75" primary tubes. Direct bolt on, gain more performance due to more air flow. Dynoed with 15 hp and 20 torque increased.