Here's a review from a forum member who's MK6 GT TDI I remapped

Rating: 5.0 out of 5
Car: Golf 140PS 59 plate
After emailing various tuning companies I was most impressed by the courteous and informative replies from Carbon Chiptuning. What must have been trivial questions for them but important for me were answered swiftly and like I said informatively.
I had only been doing some research into getting my car mapped at this point as I was unsure if the car had some sort of anti tamper guard on it to prevent it being re-mapped as that was the impression I was getting from other Golf users in various forums.
I had been that impressed with the communication from this company, that I was prepared to travel from my home in Glasgow down to Manchester to get it done. However by chance Craig was up in Glasgow on business and contacted me to see if I would like to test my car to find out if it could be re-mapped by software alone. I jumped at the chance as it would save me the long drive to Manchester.
As it happened my car was suitable to be re-mapped by software and Craig gave me the option to have it done the following day. He explained he would upload my present map down to his business workshop where one of his colleagues would configure and alter it then put it back on my car. He would have done it there and then but unfortunately I had other commitments to attend to.
At absolutely no point was there any hard sale to have it done. Craig was extremely patient with my questions and was able to explain every process he was carrying out. Customer care certainly seemed number one on his agenda which unfortunately not many companies could care less about nowadays.
The remap itself went really smoothly. It took about 20 to 30 minutes from start to finish and then I was given the opportunity to go and try it out. WOW is all I can say. What a difference it has made to the car. The power output is breathtaking compared to how it was. It is such a smooth delivery right through the rev range now. On the motorway it is such a joy to drive. Pulling in 4th is something else. My only regret is I never got it done sooner ;o)
Craig contacted me a few days after carrying out the remap to enquire how I was getting on with it and to see if I had any issues. Again fantastic customer service. However I was delighted with it. One other thing to mention is MPG. I'm not a driver that drives with a light right foot so don't really pay attention to my MPG but while doing some urban driving the other day my MFD reported I was over 70MPG. This had never been above 60 before!!!
Would I recommend Carbon Chiptuning? Definitely yes.
Would I buy from again? Definitely yes.
If you are in 2 minds, I'd give them a call as they can reassure any concerns you may have.
Tony