Timevalve advertises that they use 321 stainless steel, an alloy that nominally has 18%Cr-11%Ni. I've been paid good money to examine exhaust material issues for an auto manufacturer and found that 321 is one of the best grades of exhaust material commercially available before going to exotic material (nickel-based, or titanium). I don't believe Timevalve exhausts are plated - no need to.

__________________
95 E320 Cabriolet, 169K