I am not an expert whatsoever at thermal shielding however I agree that an under hood application is different than an open air application. It is my understanding that the main reason for an external wrap/coating application is to retain more heat inside the pipe with a “potential” secondary benefit of controlling external temps.
That being said and again I try not to engage in anything technical that I have not personally done so here we’re my observations. The 4 used Storm WSBK header manifolds that I had were all Ti, they were all wrapped 8” from the flange and they were all cracked (replaced by Storm).
I personally wrapped the vertical header 8” from the flange on my last build playing around with things and using the IR gun saw no measurable difference between the bare pipe and the wrap once the engine was at temp so I abandoned the project. In my opinion, for my application, I could see zero benefits in considering an exhaust wrap. To compound matters, the lava wrap I used was quite messy to use. I cannot speak for thermal coatings as I have no experience with them but there may be something there.
