Media blast it and then seal it ,looks like "old" cast aluminium,or media blast then u could polish it like aluminium,easiest and long lasting with little effort in upkeep is going to be aluminium powder coat look.If u were to media blast then remove all the casting seams and sand the runners smooth and then have it silver powder coated would be about the cleanest its goin to look...................I think pat Mcarthy has powder coated some intakes silver maybe he will see this and post some pics.If u just want to spray bomb it on the cheap to make it not look soo bad,{{brace urself for this}}spray can bright fence galvanizing The stuff looks good too,for what it is.