I have modified several Glocks, Gen 3 and 4.
The Pyramid trigger system is one of about 3 that are very good at smoothing out the trigger pull, and allowing the user to limit the pre-travel and over travel on the trigger. This aids accuracy.
The diamond cut outs are on the connector, to designate it the "double diamond" connector from the Glock store. It is a simple, low stress part, do not give those cut outs a second thought.
This connector serves to lower the trigger pull. I believe it is a 3.5 lb type, so, it should lower the trigger pull from the factory 5.5 lbs, to about the 3.5-4 lb range.
The connector and the Pyramid trigger bar smooth out the pull because they are highly polished and coated to reduce friction. The stock trigger bar is very rough. You can accomplish about the same thing doing the "25 cent trigger job." This is simply polishing all the connecting parts of the trigger bar to a mirror finish. Flitz and a cotton swab can be used.
If you want to further reduce the trigger pull, it is possible to get it as low as 2.0 lbs. In order to do this, you need to install a 2.0 lb striker spring, higher "competition" trigger spring (helps pull the trigger) and a lower power firing pin safety spring.
That is about all there is to it...and one of the reasons people like Glocks. You can change everything.
If you find the trigger still not to your liking after you install that trigger system....think about getting the Zev V4 connector, from Glockworx. $15. It just gives you a slightly different trigger action, you might like it better. I do.
All the above said, the real value of the trigger system is to limit pre-travel and over travel. You reduce the trigger pull using a 3.5lb connector (Ghost, Pyramid, Zev) and lighter striker spring (2,3,4 lbs). The combination of the connector and striker spring will let you customize your pull. You should be able to make it anything from 2.0 to 3.5 or 4 lbs (and more actually...if you install the NY trigger etc...).
Hope this helps
Best
J
ps - Gen 4 glocks...the only difference is this raised point (punched in) on the trigger bar, where the safety plunger is. This point tends to drag along the inside of the slide and thus increase friction. It is there to help guide the bar on the safety plunger. NOT telling you how to deal with this but....google it and you will find some people filing it down to some degree and/or polishing it. Some of the after market trigger systems just do not have this.