I'll be replacing the stock Chinese regulator in my P15 soon and have located them on the Huma website. Does the stock reg have a plenum attached to it from the factory and do you reuse the stock plenum with the Huma when it is installed. Also have any of the P15 owners out there done any transfer port opening to help with the flow? It's my experience that if you don't open the TP even if you turn the pressure up on the reg you won't gain much in velocity. I'll run some pellets across the chrony before I start on the mods so I can tell which is helping and which is negatively affecting the tune. Thanks for the help.