I replaced my cat rather than fighting with re-building the mounting.
I posted on another thread (see http://www.aveoforum.com/forum/f108/...acement-21463/)
The bottom nuts on the studs on my cat were a pain. They were just rounded and rusted nubs. I took the cat off at the header. I cut the sheet-metal heat shield so I did not have to remove the upper O2 sensor and out with a couple of bolts. As my goal replacing the rusted down-pipe; I did not care if I ruined the down-pipe. I expected to get the bottom cat bolts out on the bench. ... No such luck. Broke one off. Ended replacing the cat. The studs look like they were installed in the flange before the cat was welded together. It was like it was designed to assemble easy at the factory; the possible repair/replacement was not even a consideration. (
maybe a consideration; they wanted it as difficult as possible ).
chuck