2.5's had the balance shafts, driven off of the timing belt. 2.2's did not have the balance shafts. 2.2 & 2.5 were similar otherwise, kind of like comparing a 318 to a 360. Maybe some small dimensions were different on bearings, etc. but basically they were the same. I think most all external parts interchange. I don't remember where the extra displacement came from, stroke or bore. I remember as Tony says, the 2.5 had more torque.
My 2.2's were rated higher HP, but the CS 2.5 Turbo 1 felt stronger.
I drove 12 hours round trip to pick up my last one; for a 3-hour round trip on a decent car; I'd to that after work before somebody else buys it.
