last time i called they said you have to be a glock armorer
It shouldn't be overly hard to find an armorer in your area to help you out. I am a certified armorer and would have to tell you that it's best just to leave it be. The only thing I have changed on any of my Glocks and liked was the standard connector to the 3.5# connector.
The rest of the stuff I played with just because I wanted to speak from a point of knowledge and experience when others spoke of them. None of them really made that big of a difference. I usually actually preferred the way that it came from Glock.
Also if you speak to an armorer or any Glock rep. they will tell you that nearly every part of the pistol was designed a certain way for a reason. The parts all work together is so many ways it's amazing. The professionals have tried several different configurations and it works best the way that they shipped it out from the factory.