I had Eibach Sportlines on my ride and hated them, cause the rear appeared to be lower than the front (although they werent, the rear wheel well is just more shallow than the front).

I've heard some sagging issues with ProKit's too, although I kind of doubt them because I've always seen Eibach's on tons of other kits and they work fine.

I opted to go with a Ground Control Coilover Setup with Koni Yellows (oddly enough, the coil overs use eibach springs too).

Right now the ride is comfy, not bumpy and not too stiff.. and with it being properly corner balanced I could autox nicely.