BMW F8x M3 / M4 Equal Length Valved Sport Exhaust SystemWelcome to the Valvetronic Designs cat back exhaust system for the F8x platform, or in other words, the solution to the F8x sound problem. For years enthusiasts have wanted to find a solution to the buzzy and raspy sound these cars produce from the factory. Since these cars were released back in the late portions of 2014 we all knew there is world class sound lying under all the rasp. Our mission has been to find this hidden sound and allow all F8x