pro kits lower the car about 1.2 inches...so it already voids the warranty. It's ok though, I've heard of people who have done 2" drops on their cars with no problems. It'll be ok with neuspeed sports...it's only about 1.4 inches right? I heard that eibach is more for ride comfort and neuspeed is more for performance...so my guess would be that you might feel the road slightly more than me. I doubt it would be a big difference though...regular roads should feel fine for you. I rode in my friend's car before, he had koni's, but even on good roads, you could feel the road (when my car drove on it, i didn't feel it).