Hi All

I am in the process of stripping down two ej20 motors in the hope of making one good one.. one is naturally aspirated and the other a turbo, I know the turbo has lower compression but can anyone tell me which component changes the compression ..The pistons or the heads or both?? I just need to know if the parts are interchangeable.. the motor will be going into a non turbo 1992 legacy wagon A/T . Also I have a haynes manual for a liberty but all the different engines it covers does not cover my ej20.. Is there a site anywhere with specs and tolerences?? thanx.

George