Rancho included a card with mine with several suggested settings.

I like mine at 4/4 for my bumpy dirt road, but firmer up front if I'm using it for off road.

HAVE YOU CONSIDERED cutting your bump stops in half in the rear? At least 4 of us have now done that and enjoy a MUCH less harsh slamming effect. It made FAR more difference than the Ranchos.
Here's two good threads about it:

http://www.vehicross.info/forums/sho...ight=bump+stop

http://vehicross.info/forums/showthr...ight=bumpstops