i bought my truck with a 3" spacer lift already installed. it rode like crap. the front end was stiff and whenever one of the wheels would hit a hard bump the steering kickback (not bump steer) was awful. on the highway the kickback would shake the wheel violently.
so i took the spacer lift out and put in 5100's at 2.5. the ride was slightly better. the alignment shop was able to get 1* caster. i still wasn't happy with it, so i thought it might be because of the preload on the springs. so i was going to buy 885 ome springs but decided to lower the front end and hopfully fix the ride and the alignment. what i did was set the 5100's at .85 (less preload than 1.75) and put back in the 1/2" top spacers from the spacer lift i had. i was thinking i would get around 1.6" to 1.7" of lift and ended up with 22.25" hub to fender. as soon as i drove it i noticed a big difference, which was great.
took it for an alignment and got 2* of caster but with .85 camber. the slightest drop in camber and the caster disppears quickly. so i might have to get some uca's or bend the cam tabs over.