Dinan Valved Cat-Back Exhaust - BMW X3 M40i / X4 M40i. Designed for 2018-2024 BMW X3 M40i G01 and 2019-2025 BMW X4 M40i G02 applications, this stainless-steel cat-back system uses factory mounting locations for a direct bolt-on installation without cutting or welding. Factory valve functionality is retained for adjustable sound levels. Features: • 100% 304 stainless-steel construction • Enlarged 83mm exhaust piping for increased flow • Factory resonator/collector removed • Helmholtz-equipped muffler helps reduce cabin drone • Factory valve functionality retained • Quad 3.75-inch (95mm) tips • Direct bolt-on installation using factory mounting locations • Reported gains up to +6 HP and +5 lb-ft of torque • Polished tip version Part Number: D660-0099