Chevy Down swept dragster/ chassis car 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'' primaries stepped to 2-3/8'' with 4-1/2" merge style slip on 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.