02, is it a Version 7 or Version 8? AFAIK both were available in 2002.
I don't think the internals will be entirely reliable @ 400whp. That's 300wkw and probably 500-odd hp at the flywheel. By all accounts they're good for roughly 250wkw as a safe/everyday kinda thing.
What mods do you have already? If you haven't already, a full turbo-back exhaust and more open intake will change how it drives, drastically.
You could even get a reflash and have a safe, reliable ~220wkw without too much trouble.
The Spec C turbos are really pretty damn good turbos on a street car. Big turbos are fun but when they're only getting spooled at 4500rpm and you're shifting at 5k most of the time then you'll have a lot more fun with a setup that makes 20psi @ 3000rpm and snaps the revs from 3000-5000 before you can even think about it.
EDIT: If you're fixed on changing the turbo, check out the Blouch Dominators. They're big, built around Garrett ball-bearing cores, fit the factory position, reasonably affordable and will flow more than you'll ever need on a daily driver.