This is how you know if you need a kit:

1) Install suspension
2) Let settle
3) Go get an alignment, make sure they correct your toe.
4) They will give you a printout with your camber/caster/toe #'s. Look at that. If right off the bat its -3 or more, you may as well get a camber kit because depending on your tire size/characteristics, youre going to be rotating way too frequently and its just going to wear prematurely anyway.
5) If its a reasonable # (mine is ~-2.6 if I remember right, which is pretty bad) then drive on them. Monitor your wear closely. When you see it start to wear on the inside a bit more, rotate your tires. If the new set on the fronts then wears uneven again in an unreasonable amt of time, you need a camber kit or you're SOL.