It really depends on what material you're working with. Rough aluminum casts don't usually turn out very shiny, but Stainless Steel sheet metal will gleam. In the case of cast aluminum stuff, the only way to really bring out a healthy shine is to sand and polish it. Some take longer than others, depending on how long the manufacturer let the parts cool in the dies. The longer it sits, the better the cast. Mitsubishi believed in quanity, not quality, so I'm paying for it now.

Billett aluminum (like your fuel rail) can be polished without all the sanding. Anything that's made from billett will turn out great with very little work because billett stock isn't porous like cast stuff is.