best spring for bilstein sport shock?

[markus]

im looking for something that will lower the car but wont kill my ride quality. Also are all shocks the same for E34s? Will 525i shocks work in a 540i for example?

[632 Regal]

H&R and Eibach are good but tend to sag over time, I had spacers made for the rears to raise it a bit when I change the rear shocks.