Wrapping a header on a street car is not a good idea. While the wrap can hold in heat and keep under hood temps down, it's also that heat that can cause welds to crack prematurely. Also, the wrap can hold in moisture from driving in the rain. I wrapped a header on my Civic ... once. I ended up with a ton of corrosion and pin holes where the wet wrap trapped moisture in some of the lower bends in the piping. Consider a good quality coating if you want to keep the heat in the header and out of the engine bay.

CN: wrap on race car = good ... wrap on street car = not so good.