[PetChemMan]

While your crushed exhaust and brake line are probably not related to my story, it reminds me of an incident I had. One fine morning, in my own yard, I backed my car into something ( I don't now recall what it was) that contacted the end of the tailpipe. The tailpipe got pushed through the end of the muffler, and I wound up having to replace both the tailpipe and the muffler ! Whatever it was I backed into was low to the ground, and I didn't see it as I backed up.
A moment of inattention, and a really bad way to start a day !
It did bring to mind , though, the fact that if your tailpipe or tailpipe extensions stick out past the bumper or are too low, you could get the same damage from backing into, say, a parking curb.