Hey all, I recently cut up a failed DPF that I got off a VWW forum member over here in Australia. I hope this provides some insight into the combined cat/DPF as fitted to the Euro PD170 TDI found in VW, Audi and Seat amongst others ( possibly Merc ). First is the very fibrous and weak insulative layer around the inside of the can, you can see it in the flap I cut off. As it's no doubt something along the lines of asbestos, I was wary of breathing it in! Secondly the innards of the DPF were a LOT cleaner than I thought. Seems the filter is made of full length cels that alternate at the very end being closed, and whilst the actual top was quite sooty, it was mainly full of the white ash you can see. This must be what builds up and can't be burnt back off. I actually got very little black on my hands which suprised me, but a ton of ash came out of it. Perhaps Ryan (ryder01) I got it off had it backflushed and baked or something, but I expected a lot more soot. The ceramic was incredibly strong, and laying into it with a hammer had little effect, I had to break it up with a big screwdriver and the hammer. Very much like pottery ceramic, made the same sound as it broke up, and cracked the same. Once I got a central section out, I was able to remove big chunks of the core which I will keep for future study. In all the medium was far more symmetrical and uniform that I was expecting, and the ash that fills it was a suprise being white.