Just an observation, cnc work does not make a head flow better unless the program copies somebodies good hand work. I have owned a flow bench for 25 years, I have fixed several cnc heads that did not work, I have seen several indy cnc heads that backed up, actually flowed less after .5 lift. air speed on the short side was too high. The ones you can't fix are too large of a port and the air speed is too slow. Ask a few questions before they hit the start button. And then there is the guys I know that when they got their cnc heads back they leaked water because of small pin holes in the casting where too much material was taken out. And then there are the cnc heads that are so thin the first time they get good and warm the valve seat starts to move and the valves won't seal correctly. Don't get me wrong I have seen some really good cnc heads but ask questions about port velocity and flow numbers to expect when they are finished.