For resizing the gas port/passage, BRT used to sell the CustomTune kit. You can do a DIY version, but I'm not sure if it would work with a PWS piston. There was a guy, Randall at AR15barrels, that did the CustomTune method in the barrels gas port. I'm not sure how it turned out and it was a long time ago.Yes #3 on the gas. In stock trim it would run just right at 3 with no can. Haven't shot it without the can with the flatwire xh buffer setup.
Thanks for the info I will look them up.