The BMW X5M and X6M are already powerhouses in performance, but from the factory, the S63's soundtrack leaves room for improvement. At Valvetronic Designs, "decent" isn't enough so we developed the ultimate valved exhaust system to amplify both performance and emotion. Connecting directly to stock or aftermarket free-flow downpipes, this system features a 2.75-inch free-flow design from inlet to outlet, running completely unrestricted to the exhaust tips. Through testing, we found that an unresonated configuration produces the rawest and most exciting sound, delivering maximum character without sacrificing drivability.