Pistons should be identical. The stroke is what makes the difference. For example, the Supertech pistons I have are 11:1 for a 2.3 but 10:1 for my 2.0. The crank/rods are what make the difference, although I'm not sure which or both.
'06 forged, turbocharged, meth-fed Ford Focus. New 1/4 numbers soon.