i was putting on a megan s-pipe last night and like many of you, spent 20 minutes trying to get it out of the pipe and stripped most of it. BUT...instead of having to go get another sensor, this guy at the shop told me to clamp down the o2 sensor in a vice and then turn the pipe. it worked, no joke, immediately. o2 sensor still works, everything came out fine. i dont know if this will work on headers or not but if youre having problems with either, its worth a try.