Stokesey have a look under your rear arches - there are springs! You get 4 springs in the Eibach kit - dont need to do anything with the beam. The suspension is completely different to the torsion bar setup that earlier Clios had.
The Eibachs certainly improved the handling of my car. It corners with a lot less body roll, and is more composed on bumpy or broken-up surfaces. The ride is firmer without being anywhere near uncomfortable.
Costs? I paid £126 for the springs including delivery to my house, and £45 for a local garage to fit them. Add on another £20 or £30 to get the wheel alignment corrected afterwards - this is essential it WILL be out.
Hope this helps - its the best mod you can do for a couple of hundred quid.