My coil-overs are 12kg/12kg and they are fine, I've even ran them on the stiffest setting for daily driving without a problem and the road to my house is one of the worse. It also depends on the damper as well, I had d2 coilovers on my old celica, and it was alot more bumpy and rough then the coilovers on my s2000 atm.

DMS coils are great, I wouldnt excatly say they are affordable, neither are they worth if for a street driven car, hardly even woth it for a car that goes track less then 5 times a year.