Springs and Subframe combo
FYI, I have hypercoils with SLP Bilsteins and SLP bolt in subframes! The hypercoils with SLP bilsteins are a nice combo!
Just my .02
Bilstein HD's will handle many different combo's. So will Koni SA fronts and Bilstein HD rears (this combo can also lower you 3/4 in front and 1/2 in rear).
I just put Hotchkis springs on my car, and again, made a HUGE difference. I did leave the springs on for now, even though my car is a 2000, it only has 12K miles on it, so I left them. Just didnt have the extra money right now, but the springs still made a huge difference in how the car feels/corners/launches.

