Im wanting to add some length to my kahr cm9 grip and was looking at a galloway precision +1 extension. They are the same price as pearce grip extensions abd add a round but my real corcerns are with usng a stock 6 round cm9 mag spring with the +1. Since adding extra area in mag that would essentiallly weaken the mag spring. Should i get xtra power spring or get a stock 7 round mag spring? Anybody have any experience with the galloway +1 extension or other +extensions? Thanks