I've never tried using the dry moly as an exhaust coating, however I have had some over-spray hit mufflers of heavy equipment and it sticks around quite a while. I love the stuff for lubrication of hatch latches, grader circles and moldboards, etc.
https://www.google.com/search?rlz=1C...39.ZT8KfyW8Zhc
The Loctite version certifies anti-seize protection above 2000*F. Might be an option. This is the product I regularly use at work.