I don't know... I've never worked with a QR25, I don't know anybody that's tried to turbocharge one. There's a lot of stuff you'd have to sort out, like engine management for example. There's no ECU available for the QR25. And then it can't take too much forced induction because it's an open deck block, it has thin ring lands, soft valve springs... there's a lot to be figured out.
Since no one has done it yet that I know of (though area 51 has a supercharged one?), there's one pretty safe way to do it; basically replace a lot of the internal part of the motor. This would mean the pistons, rods, and valve springs. I don't know if anything else needs replacing yet. I guess if you don't go over the stock rev limit, the stock valve springs would be okay; you'd have to worry about hitting it a lot with a turbo though, especially in the first 2 gears. You'll also probably need to sleeve the block. For the engine managment, since JWT doesn't have a program out, the safe bet would be a stand alone system. You could get away with those black boxes but I wouldn't try!
Well, there's a first for everything so they will be a first turbo QR someday.