Forget TRW.. They are not very popular here in Portugal for several reasons
The kit name is "TRW200" and "TRW250" but that's not the power you get with a turbo and an intercooler...
Not a chance.
I am aware of the 2.0 HDI being coaxed into about mid to high 160s as far as BHP goes, and high 270s to early 280s for lbft of torque and still be reliable.
Best I have seen that can reliably be believed is 189 BHP and 356lbft torque. Not a daily driven vehicle.
How you can get almost twice that with less displacement from a variant of the same engine without internal work is certainly questionable at least.
I would be interested to hear what the "tuning company" have to say.
Bigger turbo and intercooler are the way forward with older IDI engines like the XUD where you can infinitely adjust fuelling, at the side of the road even. Generally the HDI boys don't even change their turbos to achieve those figures, just add an intercooler and get somebody competent to sell them an engine map.