A GTD standard is plenty quick enough for UK roads in fairness. Its noticeably quicker than my old Octavia vRS 170 CR......its not staggeringly fast off the mark but then no 2.0 4 cyl diesel is really.....once on the move its v good indeed.
If it were my own car id probably consider a DTUK box, though I still have my reservations over long term wear/tear effects on the engine, gearbox and clutch and the near £400 they command seems rather alot of money...but its undoubtedly the best tuning box out there.
Mapping is ultimately better but its naturally a calculated risk to void the engine/gearbox warranty on a new £28k car. Lots of people do it but not sure I could bring myself to until the car turned 3.
My car is a company vehicle so Im stuck with it being standard but IMHO no biggy, is a great car with lots of licence losing potential anyway!
I am happy to leave my GTD well alone in terms of remaps - maybe when it's out of warranty - like you, after 3 years,
It's quick enough for me, though i realise speed and torque has an addiction.
I've actually decided that the fastest MK7 produced is a Bluemotion Golf in Red. I've come to this conclusion because from the slip road onto the M5 out of Exeter to the turn off for Cullompton - this particular Bluemotion was right on my arse and I moved over a couple of times so they could pass, no, just staid with me, way too close!
So there you go - buy yourself a red Bluemotion Diesel Golf!
James
For me, 150 is still plenty of poke, a great motorway mile eater and like pipsyp said about the GTD, plenty licence losing potential!