from experience...it dosn't hurt your car to lower it. but if you lower it too much over factory , you will adjust your camber(makes your car look bowlegged) you will need to correct it with a camber correction kit.
i prefer a .50-1.50 in. drop. it looks much better than factory and it feels like factory. anything over that and you will screw up your camber and give up ride comfortability.
all springs have a sport kit and a race kit.(ie. eibach sport, h&r sport, neuspeed sport, eibach race, h&r race, and neuspeed race. etc). sport kits have anywhere from .50-1.50 drop while race kits have anywhere from 1.75-2.50+ drops.
bottom line. its all about what you want. do you want a stock ride with a sporty drop or do you want a terrible ride with an, i must admit, really nice look?