I recently had the back box removed on my 2.0 TDI and a nice custom pipe fitted. I just can't get enough of the sound it makes!
Cat back (back box delete & DPF) Audi A3 2.0 TDI 8P 2009 - YouTube
Cat back (back box delete & DPF) Audi A3 2.0 TDI 8P 2009 - YouTube