Piotr is right on regulating the height but coilovers do make a very firm ride. And my advice would be not to buy cheap rubbish.
Your other options are lowering springs with matching shocks from companies bsuch as KW, H&R or Eibach.
How low you thinking of going? Abd what's your budget?
Obviously for ultimate stance you could go on air ride but you need deep pockets.
Cheers
Steve