Silverado & Sierra 1 3/4" Longtube Headers 1999-06 (4.8L, 5.3L, 6.0L Engines) Mandrel Bent Tubing, CNC Machined Flanges Race Version with "NO" AIR/EGR Fittings, 304 Polished Stainless Steel 1 3/4" Primaries/3" Collector, Standard Graphite Manifold Gaskets 1999-2006 (2wd & 4wd) Gains over 25rwhp