I finnally find out some sort of sollution. Bilstein still makes B6 Sport for the MB6. I bought a set for the rear of my car. However, I haven't installed them yet, because the spring plate came short for the OEM springs. I'm waiting for a solution from the company that sold them to me. If there's no solution, I'll make a plate for the spring a little bigger. The B6 shocks are completely the same as the OEM ones, but much stiffer, and are of very good quality.