2003-06 Chevy/GMC 6.0L Truck headers. These headers come with air tube fitting on primary and 1-3/4" primaries that flow into a 2-1/2" slip-fit collectors with O2 bungs welded into the collector that flow into 2-1/2" High-Flow cats. System includes High temp RTV silicone and 8mm Header Bolt Kit. Stainless Works Header Kits are built from corrosion resistant 304 stainless steel, our headers are TIG welded for strength and durability at our state-of-the-art facility in Streetsboro, Ohio. We stand by our products with a lifetime warranty on material and craftsmanship, and as always, our products are proudly made in the USA. Features: Long Tube Header Design 1-3/4" Primary Tubes Smooth mandrel bends optimize exhaust flow Fully TIG welded for strength and beauty Built To Order in 4 Weeks