The porkensioner is an automatic tensioning system which uses parts which are used on a wide range of Audi and VWs.
The bracket is $149 if you dont want to retain the airpump, or $189 if you do. The rest of the parts can be sourced locally or the whole setup can be purchased from Roger www.928srus.com or Rog100 on the board here.
It is a very worthwhile upgrade.