I have run these spacers on both my cars, have to cut off outer mounts on the front bi-pipe, but no different than running them on a 2.7t with apr pipe or rs4 setup. never had any problems for the 10k miles I had them on my previous car.
They work great, keep intake manifold at a much steadier temps, longer time of intake temps getting high, and cools down alot faster.
And BTW I do have 6 more sets available. I had to have 10 sets made on custom order