Martin's got 'em in his car. They ride pretty smooth for the most part. His are much better now that he's cut the bump stops on his Bilsteins. I'd think that's a must do with these springs.
Personally, they are not my favorite setup. Too low and a bit too soft for how low they are.
I haven't riden in too many cars with different springs so I can't really comment much. I can say that prefer my Dinan setup a quite a bit over the BavAuto setup.
If I were looking, I'd take a hard look at the Sachs kit. Matched spring /shock setup with a nice ride. Haven't seen anyone unhappy with that one. Not so with the BavAuto setup.
Bellevue WA
90 535iM - not much stock remains. 3.7 liters, ported head, cammed, 3.73 diffy, M5 brakes, MAFed, yadda yadda yadda
86 Porsche 951 - Track Toy