John, It also depends on the tyres. I run 26 psi (1.8 bar) with the Vredestein TTrac2. The tyres are controlled and still offer more comfort than the Conti CT22.
22 psi is far too little for me, spongy and maybe for slow cruising. Does the 2006 4/4 have lowering blocks? I removed them on my 2014 4/4 and the rear axle is much more controlled. I don't think I need a panhard rod.
