i think this is my area of expertise.
hybrid long block is a inexpensive way to go. the ej22 bottom end is strong and the EJ25D heads flow numbers rival that of a STi.
sooooooo im gonna give u a short run down.
so if your car has an EJ22 in it its slightly harder.
i personally would recommend a car that has a 2.5 in it already. why?
1 beacuse the Ej22 manifold and the EJ25 heads are not compatable. so you wouldnt have to swap it.
2 EJ22s are easyer to come by becasue the damn things never break.
3 the Ej25 ecu revs to like 6600 rpms before fuel cut. the EJ22 hard fuel cut is 6000. (soft fuel cut feels like 5800 to me)
4 you dont have to have timing covers and crap like that.

also, there are quite a few parts i would recomend having to help with fitment.
legacy turbo take-off parts are going to be your friend.

- Idle air control valve (the 90-94 legacy turbo one has an elbow on it that makes fitment easier.
- unless you have engine management in mind, use a VF10 or VF11 because they have a plasitc elbow on it which makes fitment much simpler.
and your injectors will only handle 7-9lbs. and both those turbos are good till over 12 psi.
- AFR guage.
- any OEM (JDM or USDM) exhaust manifold except of of the EJ255/EJ255 (because they require a different oil pan.
- oil return and oil feed lines from any DOHC turbo car, EXCEPT the twin turbo engine.
the EJ25D heads have the oil galley for the turbo feed/return. not mod required.
- Forester XT intercooler.

also be prepaired to cut your cross-member. or swap a legacy turbo cross-member in because the turbo cars have a notch for the up pipe.

i gotta run but if you have questions about it post in my build thread. im more than happy to answer questions on it.