Awesome gti used them for apr on my s3, there good but expensive.
R-tech performance as stated above, not used them myself but they always get great reviews. I'll go to them myself in the future but because there a couple of hours from us manc's then it's best to get all future mods you plan on doing fitted first so you don't have to go back for a map session after every upgrade.
V12 chip tuning in Trafford park, guy that owns it is called scott. He's decent enough, I've used him to map 2 diesel cars and a mate used him for his stage 2 mk5 gti. He doesn't do generic maps, there fully custom and written by him. He's recently had a rolling road fitted to. His maps are less than £200 and I haven't got a bad word to say about him.
Unicorn motor developments in Stockport, not heard much about them, they supposedly also do custom written maps and have a rolling road