Supposedly I can take it back for any reason. I asked and made sure first that they didn't have a problem with aftermarket suspensions and their lifetime plan. They told me at the time that as long as they can adjust it, it's fine. The only prob is that everytime I go there, the manager seems to be different.
I usually keep my car pretty high though so it's not a problem. I just drop my car for meets and such. Most recently, I got it aligned because I had to swap my axles and since I undid a few of the ball joints, the alignment was a little off.