So far so good - Volquartsen Firearms TG9 Trigger Ruger PC9 Assembly

This is a very well made item. That's immediately obvious when you handle it. Heavy metal construction unlike the OEM plastic one. Installation is simple. If you do get confused theirs videos on the net to walk you through. I have only had a chance to test fire the gun a couple of times after installing it. It functioned normally with rated trigger pull weight. I will withhold my final rating until I get a chance to put a few hundred rounds through it to see if I have any of the light primer strikes that some others have reported. Assuming I don't have any light primer strikes I would 100% recommend this as a very good (but unreasonably expensive) upgrade to your PC carbine. I understand this item has been discontinued by the manufacturer. That's something to keep in mind if you ever needed customer support... their probably wont be any.
one last note: If you have an aftermarket recoil buffer (like the one Mcarbo makes) you'll have to take it out and put the stock one back in or this trigger group wont work properly.