These stainless steel drag race headers are engineered with the correct firing order pulse sequence in the collector for ultimate race performance. They feature 3/8" thick laser-cut stainless steel port flanges (also contoured for a perfect fit on a variety of cylinder heads) and "true merge" slip-on collectors with expansion cones behind collector exits. Slip-on collectors allow for primary pipe length tuning to meet individual requirements. Brackets and tubes can be welded on after header is tuned. Hardware, sensor bungs,
collector tabs, and evacuation tubes are included for installation.