AFAIK, we don't have too many choices for MB tuners. In my GM, they have 4 02 sensors. 2 pre and 2 post. The post measure the effectiveness of the cats while the pre measures the effectiveness of the cats. So, if you have no cats, you will throw a check engine light. It might also do other things in this new car so we don't really know what will happen. Therefore, until we have people that can remove the error code and thus not trip the SES, we cannot just bypass the cats.