Depends on your goals for the Ex. I did stage II injectors from Rosewood knowing I'd have to do something about the turbo (Stage IIs will kill a stock turbo they say, and mine is starting to make some funny noises in boost pulling my toyhauler). I do have custom tunes, and it's still rather difficult to keep it from rolling coal when not pulling, so that's something to consider as well. I do have plans for a GTP38R with a WW once I get the funds back up after doing balljoints and hubs.
If you do not want to really modify much else, I'd get Rosewoods stage I injectors and custom tunes, get rid of that superchips