-NOT sure I understand WHY you wrapped the headers? Besides to give the mice a place to call home and smell delightful when you fire thee ole girl up......
Turbos use heat from the exhaust gases to spin the exhaust turbine which in turn spins the compressor wheel forcing air into the cylinders. The least amount of heat lost via header/manifold/crossover pipes the better. It can also be used to protect anything that's sensitive to heat that may come into contact with the header/manifold during operation.
Awesome build. I am a diesel guy so turbos are something that I'm use to. Naturally I'd love to have a turbo'd motor in my Duster! Maybe one day, for now ill live vicariously through you guys with turbos lol.