FLOWTECH I STANDARD FULL-LENGTH HEADERS, SATIN BLACK HI-TEMPERATURE PAINTED -- 49-state legal; Not for sale or use in California; Cannot be shipped to California addresses; 1.625 in. tube diameter, 16-gauge tube wall thickness, 3 in. weld-on collector, standard head flange; All mounting hardware such as bolts, nuts, and premium gasket are included; Full-length style; Round head port; These headers are precision-engineered and leak-tested to provide the maximum performance and fuel efficiency of your engine; Formed from specially selected 0.060 cold roll flash controlled tubing with high quality electrostatically-applied satin black paint finish; They feature Flowtech's exclusive, thick, and mandrel-formed power plenum collector; All ports are precisely fitted and finished with sturdy and leaf-proof o-ringed port seals; Must modify stock exhaust to retain catalytic converters; Applications with oxygen sensor use reducer part number 10105 for 2.5 in. 3-bolt flange or part number 10110 for 3 in. 3-bolt flange; Must modify lower a-arm support bracket on 79-81 models, pre-70 vehicles with exhaust manifold mounted alternator/generator use bracket part number 10031; Will not fit angle plug heads; Legal only for off-highway or racing use and pre-emission-controlled motor vehicles or engines.