I had my Ibiza done by chippeduk, same engine as your golf, and definately recommend them. You will get about 170/175 bhp and around 410 Nm. When I got it remapped I was told that the clutch would be fine, but after driving it from Marseille the flywheel had broken and contaminated the clutch (£700 to replace them). I'm not sure if it was the extra power that caused it but I suspect it was. You should definitely look at getting an uprated clutch if your thinking about a remap.
Other companies which are meant to be good are Revo, AMD, Jabbasport etc