I wrap my head pipes only with Thermotec wrap...
Is it really necessary? nope
Does it help? well a lot of heat quit coming out the plastics and it does help power (although probably very little) The amount of heat coming out on my legs is down maybe 85%?
I can tell you that it works much better than any of the spray coatings I have used but it is both more bulky, and a bigger pain to use.
JetHot coating has worked well on our race car headers "Zoomies" (these pipes can not be welded even, they will blow apart)
Cons:
WIll shorten the life on most pipes by a bit, however, I have never seen a bike with worn out pipes (other than OLD OLD bikes)
Do NOT use on Titanium pipes.. it will allow the metal to change properties and they will become brittle and break
Do NOT over wrap.. double overwrap is too much.. again the pipes will run too hot.. a 1/2" overlap of material is plenty.