Think Rockhopper meant the Mini One and the Cooper.
Had an Alfa 156 2.4 JTD with 30% higher capacity turbo, bigger Intercooler, remap, plug in box for further fuelling mods, plug in box to control boost pressure, water injection (which also allows the edition of Methanol and Nitromethane (same benefits as Nitrous Oxide)) hand made exhaust with removable Cat, professional induction system lots of other minor adjustments/mods, (and some very big brakes!).
In petrol terms, only a 911 Turbo came anywhere near the torque this thing chucked out, the BHP was only low to mid 300's but it was devastatingly quick as first gear just wasn't necessary! Pull away in second until the Kevlar or Ceramic clutch (depending on which week it was) gave up the ghost!
There are definitely weak points, it's not the engine, and you won't have to worry until you're into much more than a remap or plug in tuning box.
At 48,000 miles the Alfa was on its 2nd gear box (first one having been rebuilt once as well) and 6 or 7th clutch, I really did lose count!