The WRX sTi has a 2.5, I'm not sure about the Evo, but i think it might be 2.8.

 

the evo is a DOHC 2.0l (4g63) ITs an updated version, the tranny is on the drivers side of the motor, rather than the passenger.

To the original poster, It can be done. The only thing holding you back is the transmission. It would be alot cheaper to build a MTX tranny than the auto. Like i said it can be done, but most of your tranny parts will have to be custom built.

k3v