i like the sportlines myself. although I didn't go with these, they offer a good drop without sacrificing too much ride quality. Personally, I wanted a more aggressive drop and chose the Intrax springs. Paired with the illuminas and a few other goodies, the handling is unreal.
Then the sportlines will be too much. Go with the Pro-kit or Steeda springs. You can install Steeda X2 ball joints for another 1/2" in front if you feel the need.
Eibach Pro-Kit here. The Pro-Kit is a progressive rate spring. It dropped my car just under the specified 1-1/2 inches. I like the smooth ride and the handling is way better than stock.
I got mine lowered 1.5". Went with Eibach (see sig). Rides great, takes corners awesome, but look out for those bumps and steep driveways. I really have to watch out, to keep my exhaust system from scraping. If you think it sounds bad to hear finger nails on a chalk board, the sound of your headers or cats touching the ground will really make your spine tingle!!!
Where's the cheapest place to buy Steeda Springs? There's a place by me that sells them for $190. Is that good or is there a cheaper price anywhere else?