You can get it beadblasted by most engine builders or even polishers. My blast cabinet isn't big enough for a manifold, or I'd help you out. I would highly suggest my polisher (Al Reed polishing in Anaheim) blast the manifold and he can clear powdercoat it. He is polishing the logs, risers and plates for me as well as blasting and clearcoating my Stealth manifold (nothing looks worse than bare aluminum after a season of exposure to the elements).