I have a zirconium finish on the exhaust of my 2.6, both on the cast iron manifolds and the stainless-steel Y-piece that joins their outputs together, and can't honestly say I've noticed any difference in heat soak. I was offered a choice of colour and chose silver, but the finish pealed off the stainless in no time, leaving the white base, which looks OK in its own right and, 15,000 miles on, still seems intact. So if you go this route and have the option of omitting the finish coat, that might be worth considering.