You might want to have a look at Chipped Uk's ST3. If you can pick one up on a group buy on any of the VW, Audi, Seat or Skoda forums you'll pay about £300 and you get two maps. New maps for you new car are only £100 each.
I had an 2.0tdi 140 audi and I initially went for economy and race - economy was circa plus 28 bhp and plus about 4mpg, race was about 195 bhp but was too smoky for me so they gave me fast road instead - much better for road use.
The Economy map will give you a much smoother power curve and better mpg than a standard 170, easily as quick and nicer to drive without the big torque spike.
The Fast road map is more exciting than economy, but still slightly smoky (not uncommon with powerful mapped diesels) - either map will make your car capable of 'suprising' many on the move, will also put a big grim on your face