Originally Posted by Tenament
if you're in the process of "stroking out" the STi block then I don't think you should a) have a problem figuring out what/why you need stuff from the WRX drivetrain b) hijack other threads >: )
Haha, something tells me this person shouldn't be "stroking out" their '11 STi block either.
OP, STi intercooler will be a good upgrade for your WRX. If it comes with the y-pipe, all you'll need is a longer turbo-intercooler coupler and a 3"x2.75" throttle body coupler (check me on that measurement, off the top of my head).
Helps a lot with intake temps / heat soak, especially if you're running a slightly bigger turbo (VF43 / 18g).