Porterbuilt Questions (Noob)

[GoaterAz]

Hi guys, I had a few questions that came up during my suspension research that I was hoping to learn more about.

Trailing Arms:

I was wondering how exactly the Porterbuilt trailing arms lower the rear of the truck by 1" or 3". Is the lower coil spring perch lowered by either of those amounts to achieve that drop?

Has anyone weighed these compared to stock trailing arms? If so, what was the weight savings?

I want to run a 6" static drop and was curious if there were any advantages of running the 3" lowered trailing arms with a 3" drop spring compared to the 1" lowered trailing arms with a 5" drop spring?

Adjustable Trailing Arm Crossmember:

I can understand how the multiple mounting fore-aft frame mounting points dial in the rear wheels being centered in the wheel well, but I can't seem to wrap my head around what the multiple trailing arm mounting locations dial in? What exactly is 'instant center'? Are the multiple frame mounts the 'big adjuster' and the multiple trailing arm mounts the 'little adjuster' for the wheels being perfectly centered?

Also, Has anyone weighed this compared to stock trailing arm crossmember? If so, what was the weight savings?

Thanks in advance!