Is it possible for my catalytic converters to go bad on my M5

Any luck on your issue? I too have an '06 M5 (but with 117k miles) and have been intermittently plagued with Increased Emissions faults, but no decrease in performance. I waited for the engine light to go off (maybe a couple of weeks) then headed straight to get my emission test done and it passed. Days later it came back on again. I took it to Global Imports (never been my favorite place) who determined BOTH catalytic converters need to be replaced and that should fix the problem. Cost for both converters (part only) is $14,000. Needless to say, that ain't happening, yet at least.