I had this on my last 100. It had ARB bumpers front and rear and the AHC was not that great prior to this. When reversing a trailer into one of the jobs we had, without fail it would drop to the low setting.
I tried HD old man emu rear springs, this made it almost unbearable over speed bumps as the dampers on the existing AHC could not control the rebound.
The solution was a set of the airlift bags and the compressor set up that is optional. Could set the pressure at what suited my loading at the time and not worry any more about dropping to low setting or those blooming hd springs as they were changed back to standard with the airlift fitted.
My only complaint about the kit is the rubbish clips for holding the hose to the bags, the other parts with the compressor kit were push fit like the speedfit plumbing fittings and these worked really well. If you lost pressure it was always because the clip on the bag was not working as designed.
