I havn't got much faith in z-valves, phase 2's, pro-mags etc.
The best results I've got from my mag were from adding the complete RT on / off assembly with an e-mag top o-ring, and a level 10 bolt. I was running this on a FIELD RENTAL spec valve and it out performed my eclipse valve and another pro-magged valve.
This set-up does need Air to work properly, but then again if your not running air on your mag, then that would be your best upgrade.
Hope this helps
Ian