There are many problems when you lower w/o, an idea of why you want to lower. Are you lowering for looks or for race? Drag? Auto-X?
If you are concerned about looks, well then the Eibcah prokit is an excellant choice along with sport shocks, Bilstein, Tockico, Koni.
Would be great with little sacrifice in ride. yes it would be stiffer, not horrible. It really depends after you drop it, you'll need an allignment, if they can't get your ride within factory specs then, you will need a camber kit (K-Mac, Ingalls) But the prokit is only 1.3" drop which is subtle. I always reccomend, a shock and spring combo together, it is the right way!!!
Any stiffer spring, dropping more than 2" should be equiped with at least single adjustable Shocks, (KYB AGX, Koni Yellows,Tockico Illuminas) Or Bilstein Sport which are self adjusting, and IMO give you a great ride and great handling.
Shocks and tires make th biggest differnce in handling. so if you are a performance guy keep that in mind.