It will cost you more than 1k to get over the 200 BHP mark.
A very good so called basic stage1 remap of the TDI 130/150 should yield 175/185 bhp and to save upgrading clutches etc should develop a more modest
280 lbft. Remaps cost anything from £250 to £500. So for a modest outlay you will have a more than fast enough road car which should if you are lucky not cost you anything extra in terms of upgrades.
The issues come with chasing figures, everyone wants the same or more as the next person, so some tuners will just chase figures as this is what at the end of the day makes sales. With higher figures comes more aggressive mapping. An aggressive Stage1 map with lots of torque coming in from very low RPM will cause clutch and dual mass flywheel issues resulting in both being replaced/uprated and it will also put more strain on basics like engine mounts and other components. There is no rule of thumb to tuning, what works on one car will not work on another, what one car produces another may not.
Going up another level to Stage 2 costs thousands, I reckon in total including uprated clutch kit, new flywheel, clutch bearing, new suspension, uprated brakes, uprated ARB's, air intakes, Hybrid turbos, mapping which you WILL need when going over 200 BHP will cost in excess of £3000. Now £3000 is ALOT of money, but if power is your thing then my god you will love it. Again car and tuner dependent, but you should be able to yield at least 220 bhp and 320 lbft on a very low/to no smoke map or anything between 240-250 BHP and 350-380lbft if you dont mind a bit of smoke, anything over this on Standard Injectors and standard cam will result in plenty more smoke, making your car look unhealthy and quiet embarrassing.
Putting aside chasing Dyno figures as we all know on some dyno's they are a bit of a lottery. So as a rough
guide, a golf sized/weight car should do 0-100 in 17 seconds when running 185 bhp, 15 seconds when running 220 bhp and 14 seconds when running 240+ bhp.
Stage 2 tuning has really evolved in this last year with many more VAG TDI owners going down this route and the mapping has got so much better, but like I said above the figures seem to be getting bigger and bigger as more tuners jump on the band wagon trying to offer the latest and highest power outputs, so speak to as many owners as you can and find out as much info as you can and if possible go for a spin in a forum members car to get to see and feel for yourself, as what some thinks is awesome might be terrible to someone else.