The surface under the paint is very rough, so wet sanded it (400, 800 and 1200 grit but the alloy is so soft that even finer grit might be a good idea) and then I use a buffing wheel on a drill, and a Dremel for the tight corners, with a cream polish called Autosol. But magnesium alloy = guess I'll have to keep polishing quite often to keep it nice haha.