I have ironman springs in my Jeep, initially gave a good lift, had them on for about a year and the back drivers side has sagged about an inch and a half more than the passengers side. I don't carry a spare so not really sure what's causing such a big difference.
I did an initial post straight after they were installed here:
http://www.ausjeepoffroad.com/forum/...hlight=ironman
Measurements now (with the LPG tank) are:
Front left and right around 20"
Rear left 19.5"
Rear right 18"
If doing it again I'd spend a bit more on OME.