Several years ago I had to replace the turbo on my Passat. At that time I also did a clean sweep of the intake ( actually done by Bolland Machine, a diesel shop right here in Chippewa). I also did an EGR delete, removed the 5th injector. I also more or less destroyed the cat - it appeared somewhat clogged so I jammed a 1" pipe through until I had a clear path down the middle.
Sine three years now the engine check light is on due to a faulty oxygen sensor on the cat. Never had any issue with inspection since there is no emissions testing for Diesels here in PA. The yearly inspection only includes the mechanical part of the car, not the engine.
By the way - if anybody knows how to fool the system making that CEL for the oxygen sensor go away, I'dbe much obligedto learn about it.