I picked up a set of used pre-02 downpipes and cats for my k04 build. The guy I got them from gutted the primary cats but left the rears. Unlike real piggy pipes he didn't relocate the secondary o2 bungs downstream from the secondary cats. I crawled under the car to find the best location so I can relocate the bungs before the engine pull. The cats currently on the car don't look anything like the used ones I picked up. I am assuming the ones I picked up are actual audi oem and the ones currently installed on the car are not? can someone verify my assumption?
maybe the 2.8 is different but i dont have an"pre cats" just a downpipe from the back of the head that bolts up to a set of cats . the cats are flat on the bottom . The pic you posted are not OE cats .