On a side note, do you have a cite for this? I needed to buy a complete stock exhaust system a while back and the yard would only sell it to me after cutting off the cat. I didn't need the cat, but I did need the flanges off the cat so that I could weld on the new cat in the stock configuration. I ended up walking away and leaving the pieces on their floor because they ruined it. I figured their line about federal law was just the general bullshit.
JazzMan