I use header wrap. I love the stuff. I originally installed it to cut down on that stupid tick tick tick sound from under the hood and to reduce the engine bay tempertures. works great.

on another message board I follow, this topic sparks a huge argument about how it's bad for your headers, you'll melt 'em and void your warranty, blah, bla,h blah -- the negative statements all come from people who've never used it.

HOWEVER, I have read that you should never wrap a ceramic coated header. the ceramic coat is already supposed to seal in the heat I think, but I'm not sure about any of this. can't remember the benefits of ceramic coating. I've only ever had the stainless steel ones.