Many companies dont mark their injectors. Unless the previous owner told you who built them, all you can do is send them to a builder to have them flow tested. Which in this case, I probably would so you know you have a matching set.
Right but if you're measuring boost at the manifolds, seems your restriction is the head, or the valves themselves. If the turbo is pushing more CFM, seems like pressure at the point of the head would have to raise. I fail to see how a pressure measurement at the heads can pick up on restriction...