TDI North is a Honda specialist - Civic Type R's etc
I too live in Cheshire and took my GTI to R-Tech. By far one of the best VW tuners around. Nick will do you a map tailored exactly to your car (non of this upload an out-of-the-box one size fits all).
All for a decent price too
Full health check first to make sure all is well and free aftersales advice & help too. Never heard a bad word against them.
Awesome GTI maps are cheap-as-chips and are probably written by some keyboard wizzard in china that has never even seen a MK5 Golf. They dont do any health check, just plug in and go, they also cant alter the map to suit particular charateristics of your car.
You pays ya money, you takes your choice. . .
R-Tech all the way for me - you will see what I mean if you go