I planned on wrapping the entire exhaust system to keep the heat put of the engine compartment. You think thats a bad plan?
Bob Mears
Supermarine Spitfire

My opinion is that it is a bad idea.  It significantly increases the wall temps of the exhaust system, and makes inspection very difficult.  The one thing that I would consider is coating of the inside surfaces; the primary benefit of which would be increased emissivity (reduce radiant heating) since the insulating effect of the thin coatings are small. The actual benefit is unknown since exhaust products would undoubtedly plate out on the inside surface, and the emissivity may soon be quite the same as without coating.

Add radiation baffles between the exhaust and any nearby surfaces that you do not want to be heated.  Allow air flow around the exhaust system for cooling.  Just as an example, I placed a SS baffle over the manifold/muffler as separation from the induction system, small baffles protecting the engine mounts, and reflective heat shield on the redrive, as well as on the inside of the top cowling. I added a small NACA scoop in the bottom cowl with airflow directed on to the exhaust system from below.

The exit air from the in-cowl radiator goes into the cowling, and my measured in-cowl air temps on the exhaust system side during flight are generally less than 150F – not an issue.

Hope this helps – works for me.

Al