all the -4 after pr3 means is just the casting #. lots of itr/b16/b17 came with the same casting #. the way to tell is the cams and springs and ports which mine doesnt have daul valve springs on the intake side nor does it have the bigger cam lobes. its stamped 99 pr3-4. so im assuming its a 99 b16 head with a minor port job. get itr/ctr cams and dual springs on the intake side and feel free to call it itr . again i got it in a trade when i sold my wheels, my honda days are well over just want to make my money back.