CAUTION: wrapping headers usually voids the header warranty. the reason being it contains the heat for betterr heat scavaging...etc. you already know the rest and thats why u're wrapping them. but for others that haven't tried it... try not to use in combination with thin mild steel with ceramic coating because it cracks opens the header under long hard abusive driving (i.e. climbing up and down mountain roads).
not necessarily. the best way i would try is to paint the stainless pipes with high heat paint... like flat black duplicolor engine enamel. thermotec sells their own heat wrap paint coat... but it should be the same. personally, i haven't seen any rusted stainless headers. but one warning on the application, do use the high-heat engine enamel on header and on the heatwrap itself after appication, and do soak the wrap in water...it goes to help with having a tighter wrap and lessens the rash you get from the fiberglass threads from the wrap. follow the instructions, and do allow time for break-in or the wrap to set in...
oops, soak the heat wrap in water first. then install.
and try lapping 1/2 or each round as to give it room for expansion. after install, let dry but partially damp so you can paint again and have the heat enamel set as far in into the wrap as possible.
loooonnnggg process. but worth it. you can literally grab the headers 30 secs. after shutting off the car and not get burned. removes a LOT of engine heat!
Basically anything that can be said about the stuff has been said already. That beind said lol, I got my header wrap from Lewco Specialty Products. Its alot thicker than DEI's stuff and alot better quality also.
Under hood temps have been reduced GREATLY! No lie, after driving the car hard, I can actually touch the headers for about a full second and not get burned. That may not sound like much but to those in the know, its alot.
I ran the DEI heat wrap on my megan racing tube manifold on my SR and i never had no probs and they would get to red hot?.. No cracks when i took it off to sell. and thats also the cheapest manifold made. may be im just lucky