Yep. I took the header off the car before I sold it, and it sat around my garage for a year or two. It saw a lot of wet, salty roads in WI and MN during its 30k miles of use. I sold it to a Baja owner, who told me that as soon as he installed it on his car and started it, the header cracked and leaked. For what it's worth, the header had been modified previously by a local exhaust shop; they tacked some of the primaries together to try to fix the buzzing/resonance issue. I'm sure they used mild steel wire. I don't know whether the header cracked at one of the original welds or one of the mild steel welds.
I've come to really hate exhaust header wrap. The cheap fiberglass stuff that has to be installed wet is nasty to work with, and even the nice DEI Lava Wrap, which you install dry, will chafe and come apart if it rubs against anything during installation/removal. The next time I install an aftermarket exhaust component upstream of the cats on any car, it will be ceramic coated.
I've come to really hate exhaust header wrap. The cheap fiberglass stuff that has to be installed wet is nasty to work with, and even the nice DEI Lava Wrap, which you install dry, will chafe and come apart if it rubs against anything during installation/removal. The next time I install an aftermarket exhaust component upstream of the cats on any car, it will be ceramic coated.