I got the almost-new z51 springs and shocks installed last night, took about 4 hours because I didn't know what I was doing and had to go off basic written directions without any pictures. That being said, it was pretty straightforward once I figured out unbolting the swaybar and upper control arms was by far the easiest way to let the whole hub down the furthest. Plus they don't have any adjustment so I didn't have to worry about getting them back to the same position to maintain my alignment.
Here is the old suspension out:
Kracka was asking me earlier about raising/lowering the stock suspension. The spring is only attached to the subframe in two locations (where the bands of rubber around the spring are in the pic above), like this pic shows:
The ends of the spring just rest on the circular rubber pads that are touching a flat area on the lower control arm. The pads are attached to a bolt that you can thread up or down which affects how far away that rubber pad is from the spring, which will lower or raise the car.
Shiny new front spring and shocks about to go in:
Installing the new spring, yay for no rust! I had absolutely no trouble with any bolts.
I took it out for a drive last night for a quick test, but it was 50* and damp out so I couldn't really tell if it corners any better, it was just sliding. However, it did stiffen up the ride a tiny bit which feels great, definitely more feedback now and it feels a little more like a sports car. The base springs and shocks were pretty cushy imho. Hopefully more testing in the next few days, looking forward to the cruise next weekend.