I've been qouted Ł250 all in inc P&P and then its DIY, should give me between 185-195 bhp from a 150bhp A6 2.5 TDi?

Any thoughts or previous experiences using the VP44 tuning boxes?

I know the 'Tuning Boxes' is a huge subject but I'm after quick response as ive some money burning my pocket and I want to improve/chip my car.