Chevy Upswept dragster header for Big Block with conventional heads. All tubes are CNC mandrel bent for optimal flow. Made from 304 stainless steel for maximum corrosion resistance. Starting with a CNC cut 3/8" thick flanges into 2-1/4" diameter primaries, Flow into 4'' slip on merge style collectors. Headers are fully TIG welded and back purged. Mill finish, These, are TIG welded for strength and durability. These kits come with a lifetime warranty and proudly made in the USA.