I'm just throwing this out there because I am curious.
Jay (my builder friend) and I have tossed around the idea of wrapping the header on my Vintage Roadster bike, and haven't come to any conclusions as yet.
I know that there are a lot of opinions about how it looks on both sides, and I'm right in the middle of the road; not really sure if it will fit the look of the bike or not, but we can work that part out.

My question, really is this:
Are there any serious drawbacks to using this stuff on a Savage header?
I understand that the wrap is intended to keep the exhaust gasses hotter, and therefor increase performance ever so slightly, but the stock Savage header is DOUBLE WALLED, which is unusual to me, I've always seen single walled headers on motorcycles, SO...
Since the header is already double walled; doesn't that really do the same job as the wrap anyway? Would the wrap then be redundant, and really not have any noticeable effect on the performance at all?
OR... Worse yet; would it hold too much heat in the space between the walls of the header and cause problems THAT way?
I saw someone mention in another post that there is an air hole at the bottom of the header-where it comes together-that is supposed to allow the heat to escape from the gap between the layers, and therefor relieve any pressure build-up that might happen between the walls of the header.
Anyone know if I should be concerned about these things if I go ahead with it? Or am I just over-thinking stuff as usual?  
Thanks!

a positive is that it keeps some heat in... so you burn yourself less! no more blisters from accidentally bumping the header while you are wrenching on your bike! no more melted rain suit/jacket/pant legs! or less, anyways.

Another regularly noted "negative" is rusting and moisture.

header wrap, while on a bike that is cold (not running) will keep in more moisture and will accelerate rusting. when hot, the moisture evaporates fast enough that it doesn't matter.

Should you be concerned about the added moisture if this is your daily commuter bike you store in a garage? no. Should you be concerned if this is an expendable and forgettable toy (shame on you!) you leave out in the elements for five years and then come back to? yeah, maybe  :'(

little performance things for the savage kind of tickle me. part of me gets you want the most performance out of anything you have, but at the same time, despite how awesome this bike is, it isn't a racing bike you need to have at it's pinnacle performance. header wrap won't noticeably help or hurt you, it is almost purely aesthetic, and therefore everyone has very set opinions on it we like to try and justify one way or the other but it all boils down to "beauty is in the eye of the beer-holder"  

Thanks Guys!
I really don't expect or need any kind of performance enhancement from this; If we do decide to use it, it will be purely aesthetic. I just wanted to be sure I wasn't going to get ito any serious trouble with it.

Just a side note; the header we have is old and blue, but not beyond recovery, and I won't require showroom new looks from it anyway.
Additionally, I will have a K&N pod filter, and a new muffler (possibly Dyna, possibly custom, still deciding...) with re-jetted carb to match, so I do expect that there will be slightly higher exhaust temps than stock; but this won't be all re-cammed and blown and ported and sh*t, so I won't be racing it any time soon! (maybe next winter?)

It Can have a lasting impact.

http://www.world-mysteries.com/skull_peru.jpg