Doug's Headers D452 2" 4-Tube Full Length Exhaust Header for Mopar B Body Big Block Mopar 62-72 Thick flanges (3/8 inch to 5/8 inch); no warping CNC mandrel bent tubes; accurate fit & better flow Precision formed long transition collectors; reduces backpressure Heavy gauge tubing (16 & 14G); longer life Header tubes are pre-polished; better appearance Thick flanges (3/8 inch to 5/8 inch); no warping CNC mandrel bent tubes; accurate fit & better flow Precision formed long transition collectors; reduces backpressure Heavy gauge tubing (16 & 14G); longer life. Heat resistance up to 1400 degrees Header tubes are pre-polished; better appearance