cheap coil overs are appealing, because they are cheap! better off saving a few more pounds get a proper set of shocks{koni, bilstein} and lower springs{25-40mm} used cheaper coil overs on vw mk4 golf, car handled well, but always get a bumpy ride with them
was never totally happy with them no matter how i adjusted them.
recently put koni sport shocks on a 530d{e60} and its lovely, ride is excellent and the big heavy lump does not bounce around at all.
not cheap, but worth it.