If you can't find any reviews of them on here, then there is a chance they dont have a big reputation as a Golf GTI tuner.
The advice a lot of guys on here would give, is stick to a tuner that is well prasied on the forum, that way you know you are getting a quality product with the after-care if required.
In all honesty, the latest & best mapping techniques and understanding of the TFSI are the tuners which are typically the most popular
try a search or a flick through a few pages of the mk5 general area or the performance mods section, lots of great advice and experience
Dont be afraid to travel to get the right product, plus the drive home will be great fun