Caveat: I don't own one, just sayin' what my ears think they hear out there and my eyes see online.
I've heard that almost anything you do to a Glock is an upgrade; is that right?
(Not saying they're bottom-of-the-barrel, but seems that like 10/22s, there is a very healthy "aftermarket upgrade" market for those, compared to some more expensive polymer pistols that come already "upgraded" out of the box, say. IDK, just seems to me that there is lots of room for improvement if there is such a strong supply of upgrades out there)
Is it the more basic ones that are upgraded by folks? The few times I shot a bog-stock 9mm a few years back, it (the trigger) felt a little rough to my untrained hands.