hello,new to the forum.....my 2004 Audi A4 3.0L is throwing a cel for most likely a bad cat, it's also somewhat hard to start now and is acting sluggish. First thoughts were to check out the cats, but when I got under the car today I can't seem to locate them! I followed the pipes from engine to mufflers and don't see any cat or any sensors going into the pipes. It all looks stock. Any help would be appreciated!!