yeah what he said...
Header wrap will cause your headers to deteriorate quicky for two reasons.
1) teh repeated ultra hot and cooling cycles will produce condensate which the wrap will trap and cause rust
2) The headers are designed to allow heat to escape, when you wrap it in they literally burn up
If its just one hose shield it.
If its just every once in a while, when is the last tie you gave your cooling system a good cleaning and good clean water?
