They make a variety of coils, which ones are you looking at? The higher you go, the more components you will likely want to add. The HD's that previous posts are talking about will give well over 3" on a 4door, up to 4" on a 2door. At those heights, you will want to think about re-centering the front axle, a set of adj control arms up front, brake line relocation or extended lines, new rear links (and move the rears up front), etc.

Browse the suspension faq's for more info. These in particular:
Q: What is Caster? How much do I need?
Q: What are all the components that I will need with a 3" lift?
Q: What are all the components that I will need with a 4" lift?
(pay attention to the driveshaft cautions)