I have the spring kit and the Polymer-AET Trigger installed in my SD9VE. I also polished the feed ramp and the trigger bar where it connects with the sear and the striker block. The result is a smooth trigger pull of slightly above 6 lbs with no over travel at all. The +3 mag extensions are in beta test phase . As soon as they are up for sale I'm sure you will find them on the Apex website. I think that polishing of the internals only void your warranty if you disassemble the gun further than you would do for normal cleaning and maintenance. But to be sure check with S&W CS. If you are going to polish keep in mind that you don't want to remove material just friction.