When you wrap your headers, the wrap acts like insulation by retaining heat within the pipe. By retaining more heat, you have probably retained enough heat to turn things that normally don't turn color (i.e., your clamps). I see no connection between wrapping the pipes and coil failure. That's all opinion though.
I believe that sometimes, when the heat level is high enough or the blueing hasn't been removed quickly enough, the discoloration may be nearly imposible to remove.
I have also seen ceramic coating that looks like stainless steel in appearance. Tou may want to consider that instead of black - just a suggestion.
Personally, the only reason I would use heat wrap is to permanantly hide my headers (i.e., discolored beyond repair)
Last edited by pipedr; 12/14/2005 1:35 PM.