Ok so I'm doing the Bilstein 5100 to level my truck.(2010 1500 4x4) has anyone done anything with the rear end? Like air bags or do they make air shocks? I'm concerned when I have some type of weight in the bed that the truck will then be nose high.
Set the Bilsteins to 2.1, you should still have a slight rake.
Easiest way to check your vehicles rake, and each truck is slightly different, is to measure the distance from the bottom of the fender lip, just above the rear tire, to the ground, Make sure to do this on level ground, like a garage floor or some such. Then do the same measurement at the front tire. See what the difference is between the two.
Anything less than 1/2 " of rake tends to look level and when you do add weight to the truck, it will look nose high.
If you desire teh maximum amount of lift, you can take the bilsteins all the way to 2.8, but then you will need to add a rear spring spacer. Most go with TOp Gunz Customz Poly spacer. Either 3/4" or 1".
your stock shock can handle this added height. However, having bilsteins on the front and stock shocks on the back creates it;s own issues as they are different shocks, so behave differently. I'd recommend replacing rear shocks as well.
IR bags, as you mentoned, are another possibility> I myself am not a fan of air bags, for many reasons but a lot of guys positively love them.
Air LIft 100 is a kit many use and is easy to install.
No matter which way you go, please post yoru experience, along with pictures, to help out others, who may have this same question, down teh road.
Good Luck!!!