At OSH this year I spent a good amount of time looking very carefully under the cowl of the Cirrus airplanes with the cowling removed. If you get the chance, it's well worth it. The eye-opener was that most of the wires coming through the firewall were completely covered, on the engine side, with about an inch plus thickness of high temperature RTV, nicely gobbed on in a circular pattern. It wasn't apparent what the underlying passthrough was, either eyeball or bushing. For a certified aircraft, I didn't expect that. Now, I'm just assuming it's the regular red High Temp RTV. It could be something else but it looks, smells and feels just like it. If it works for them on certified aircraft...