What are the pro's and con's of doing this? I have seen it on a few cars that come here to Antigua (Caribbean) imported from Japan. I was wondering if it is done to cars that participate in circuit races for some sort of endurance? Wouldn't keeping that heat wrapped to the header like that eventually effect the header itself? Being thinning the metal or negatively effecting it somehow? I can see it keeping heat out of the engine bay area yes, but is it really worthwhile?

 

Keeping the heat in also helps the scavenging effect of the exhaust system (or so I've heard). Not sure about the hurting the headers part, it shouldn't as long as the headers are quality pieces. I plain on wrapping mine when I get them, unless someone come forth with a good reason not to.