People with Gaz coilovers, can you measure what height you have from the ground to the rear arch? Also, would be handy to know how much droop you get when you jack the car up.

Finally, do they knock when you go over bumps?

I'll start......

Gaz Golds - They aren't too hard really.
I have 595mm from the ground to the rear arch
I get very little droop, I haven't measured, but around 50mm
Yes they knock like fuck