Don't get me wrong, I think what they can do with modern diesels is just amazing, however, I doubt I am in the minority in worrying that you're putting power output 55BHP with a simple new exhaust and remap could be risking the engine/ancilleries. For example, the torque I assume is put up a similar amount? Can everything take that? (issues like that).
If there are no issues then fantastic but I have a feeling things like this are why I get the impression Nige is slightly, well "cagey" (maybe the wrong word) about the 170BHP. Of course, I might have the complete wrong impression!
Did you know the the V10 diesel engine had so much torque it would have pulled the Toureg (?) to pieces, they had to artifically detune the tourque!