The compression ratio of a motor is determined by more than its pistons. It depends on bore/stroke, cylinder head volume, piston dome displacement, headgasket thickness, and piston-to-deck height. Putting the pistons from engine x into engine y does not automatically give engine y the same CR as engine x.

Stock CR in a USDM B16 is 10.2 and JDM is 10.4. Putting JDM ITR pistons into a B16 will yield a decrease in CR by of about 0.01. If you want to increase CR you can go with CTR pistons which will bring you up to about 10.8. If you want any more of a bump then you need something aftermarket or a thinner headgasket.