Hi Ian, with M sport you can´t fit side steps, I´m sure. Don´t know about the mud flaps. Most probably not. Before I have ordered my X5 I checked the steps, but they are pretty awkward to use. Almost as bad as no steps at all. They actually stick out from the car more than side pods. And then again, you can´t get them with M sport package anyway and I would rather have the M sport pack. Been thinking of some home made improvement to assist with the climb into the cabin. Once I have the car sitting in my garage, I give it a serious thought.