My friends with 912s wrap their exhaust with this woven fiberglass/ceramic stuff to keep excess heat out of the engine compartment. For the most part it works pretty well and does the job. I've watched them sit there with the glass "tape" sitting in water and wrapping it tight around the pipes and attaching band clamps to hold it in place. over time it frays from being hit during maintenance and eventually has to be replaced. I've also heard that wrapping exhausts shortens the life of the pipe although I don't know.
I did not like the idea of this but was well aware of the damage heat can do to oil and water hoses, engine mounts and other plastic, rubber or fiberglass in the engine compartment. I decided to try something different and see how it worked. Now that I have about 50 hours on my solution I think I can report back with my impressions.
The solution I chose to try was ceramic coating. I had the inside and outside of the header pipes coated and just the outside of the muffler because they could not sandblast the inside of the muffler.
The results so far are amazing. My friends who wrap agree and will be coating their exhausts next time they require maintenance. The heat reduction is significant. All that heat that builds up and stays around after shutdown just isn't there. There is no hardening or burning of nearby rubber components. The coating seems super strong and stuck on. No chipping or scratching even when I have hit it with a tool or something. Not saying it couldn't be scratched, I'm not willing to do that on purpose, but it is very durable.
The cost was just over $100.00 to have the whole shitteree coated. And it looks awesome! The company that did mine does all of Kenmore Air's exhausts. I did not know this when I called them, it just came up in the conversation. They said Kenmore uses the coating to greatly extend the life of their seaplane exhausts.
I wish I had known about this technology when I was flying behind the 582. it would substantially reduce the heat from the expansion chamber and muffler on the 582, and coating the inside of the expansion chamber would be so easy.