Valved Catback Titanium BMW M3 G80 M4 G82/G83 is a type of aftermarket exhaust system designed to improve the performance and sound of a BMW car. It features valves that can be opened or closed to control the flow of exhaust gases, as well as titanium construction for increased durability. 5-10 HP increase with a much better tone and sound. https://www.youtube.com/watch?v=Nkg98Htlyso&t=1s. Video Sound link on youtube!