To quote Scotty "Ye canna change the laws of physics"...

If the engine doesn't have the internals to support the boost, it will blow

If the fuel injectors and/or computer don't provide enough fuel, you'll run lean and burn the valves or worse.

You run hot and predetonate (not using premium, etc) you blow the internals apart...

As someone else said, power isn't hard - just costs money and must be handled as a package or you will screw your engine up. Creating boost is the easy part. Managing it and ensuring longevity of the engine is another.

Factory power is the best - it's all warranted and engineered. Barring that, I would do aftermarket power on something cheap - like a depreciated out of warranty Miata - where I could get a new engine for under $1K if I blew it up. Dunno if I would mess with aftermarket forced induction on a 3 year old Xterra with a much more expensive crate engine... just not worth it. That and the X isn't a sports car and doesn't benifit from gobs of HP anyway. The factor SC provides a nice kick in the pants, but the drivetrain in the '05 is a much better way to get power (more efficient engine design).