Header tubes are pre-polished better appearance Ceramic Coated: Doug's Headers D627 2 4-Tube Full Length Metallic... Doug's 2WD Truck Headers Header development and design is complex and requires a substantial amount of time and resources to do the job right! Doug's Headers D331 Doug'S Headers D331 2 1/8 4-Tube Full Length Chevrolet Truck Performance Headers 2002-13 Chevrolet Truck 5.3L 1 5/8" 4-Tube Manifold Replacement Header With Metallic Ceramic Coating Exhaust Header Thick flanges (3/8 inch to 5/8 inch) with no warping Doug's Headers D3373-R Replacement Header, 1-5/8 In, 02-07 Chevy Truck Doug's headers are carefully developed on the vehicles they are intended to fit and are re-checked numerous times during the design and manufacturing process. Every Doug's header is tuned with the proper tube size and length to efficiently remove all the exhaust from each cylinder, reducing pumping losses resulting in a dramatic increases in horsepower and torque.
