For a final finishing product lsp (last step product) waxes or sealants on silver i would go with werkstat acrylic but it isnt the cheapest of kits but works wonders on silvers especially metalics it enhances them and brings the flake out very nicely.
Just remember though that to get the best results its the condition of the paint that determine the results . If i,m looking for a long term protection combo and good finishing i use a long lasting wax first then apply a sealant on top .