Pesky, just do it!
Yes, of course, the more 'stress' you put through the car, the sooner things will fail. But just ask yourself honestly, if you do get the stage 2, just how often will you be using all 330 of those ponies? Certainly not all the time. The real secret to the longevity of a car - remap/modified or not - is to treat it properly. Never, ever drive it hard when cold, and keep it well maintained.
Obviously, the more you modifiy a car, then the shorter the intervals become between maintenance - oil changes are a classic example. And you will also need to only use higher spec parts - it wont do any good to get some cheap oil from Wall Mart or Lidl - and expect it to properly protect a 330 PS monster. You should only use high quality stuff, like BP/Aral/Castrol, or Fuchs or Motul, or OMV oils - of the correct spec.
Finally, for the record, even a bog standard GTI, if badly abused - can fail much earlier than a modified but well-cared for car.
HTH