This has been talked about a bunch of times. There is no magic equation out there to determine the longevity of your car/engine/turbo.
Increased power could certainly expedite the wear process. In addition, the tune you have plays a huge part in the process as well. Coupled together, you could have a recipe for disaster, or... not.
There are guys on here that autox at stage 3, and they are doing fine. There are also a number of members on here that have failures with no mods whatsoever. Proper maintenance (oil changes, checking your oil, banjo bolt maintenance, etc) can/will also play a major roll in your outcome.
It's a bit of a roll of the dice to some extent, however you can control the utilization of a quality tune, good maintenance habits, decent fluids, and building the car within the means of the equipment you have installed.
... Not to mention driving habits and general condition of the car prior to modifications.