when I received my rig, it had the OEM******of the P30 springs with airbags, and shot shocks but with a coilover extra spring.
I installed BILSTEIN (BEST SHOCKS EVER!), but loosed the coilover, the shot shocks where thin compared with the Bils, so I could not put back the extra spring, I did installed airbags (against recomendations of the hendersons) connected to an AIR LIFT DUAL CONTROLLER, the kit comes with an air compressor, dual needle gauge and switches for inflate either side of the front airbags... I CAN ADJUST RIDE HEIGHT, OR FIRMNESS, OR in limited ammount, THE LEAN OF THE RIG ON THE FLY!!!! MARVELOUS!