I'm pretty darn sure AlaskaVX ran the 5100 series bilstein's with piggyback resevoirs and he had issues when doing off-roading...I'll search the links & post them for you.
http://www.vehicross.info/forums/showthread.php?t=7619
http://www.vehicross.info/forums/sho...light=bilstein
http://www.vehicross.info/forums/sho...light=bilstein