Majority of headers are all mild steel that are mandrel bent. Stainless is $$$ to do, requires TIG welding and there aren't any new vehicles using the venerable AstronI/II in front of rear wheel drive. And now the EPA has turned full fascist by cracking down hard on aftermarket performance parts suppliers. If you can get a set of headers new anywhere now, you'd better hurry before the sale of them are banned