It seems that you all are assuming the EJ22 and the EG33 have identical chamber volume on the cylinder heads. Is this a given or has this just not been adressed? This would be just as critical in determining compression ratio as the pistons themselves.

I vaguely recall my friend's (SVXtasy) own research on this matter to have discovered that fitting EJ22T pistons into an EG33 was both possible and would have netted a compression ratio of 9.0:1 or thereabouts, citing the cylinder head design differences between the two motors.