A few people have been discussing tuning boxes for the 2.5tdi recently. I fitted one to mine on Friday so thought i'd add a review/reccomendation.
I had been looking for a long time on loads of different forums for reviews of certain tuning boxes and came across one from http://myworld.ebay.co.uk/tdtuningltd/ . This one had a few good reviews, and was about Ł150 cheaper than their usual price. Plus the seller was local so i drove up there to pick it up because I hate the feeling of waiting for a new toy to arrive in the post.
The installation was easy, it plugged straight in. The longest task was fixing the wires back with cable ties. Took 5 minutes tops.
I took it out and straight away the car feels way smoother and what I can only describe as lighter. (Probably the added torque helping the car move with less effort)
The car still isn't super quick, but for a heavy car it pulls relentlessly in 3rd-6th.
I had about 100miles in the tank going by my trip comp. but when I fitted the box it only lasted 40 miles. I must admit I wasn't driving with economy in mind. After filling up again and doing 100 miles of testing acceleration in each gear it looks to have settled down to the same sort of mileage I would have expected before i fitted the box, but time will tell.
All in all i'm very pleased with the product & would reccomend it to all 2.5tdi owners.