yes, you are able to swap an sti motor into your 4eat. Couple of things to think about:
1. AVCS control
2. upgrade TC and VB + tranny cooler?
Depending on how much power/turbo you want to add (if just going with a VF series turbo-type power), then you probably don't need to do anything to upgrade your 4eat.
getting close to 400 awhp equivalent, you would probably want to upgrade (i.e. tc, vb, and mabye even IPT 4eat build).