Dinan Valved Cat-Back Exhaust for 2018-24 X3 M40i/2019-25 X4 M40i - D660-0099

Transform the sound and rear styling of your BMW X3 M40i or X4 M40i with the Dinan D660-0099 Valved Cat-Back Exhaust. Built for select 2018-2025 G01/G02 M40i applications, this full cat-back system combines TIG-welded T304 stainless steel construction, enlarged 83mm piping, retained factory exhaust-valve functionality, and a true quad-tip layout with four polished 3.75-inch outlets. Dinan reports maximum gains of 6 HP and 5 lb-ft of torque at 6,600 RPM while cutting approximately 7 pounds from the stock exhaust system.

Rather than relying on the factory single-to-dual arrangement, Dinan uses a larger, freer-flowing single primary pipe and removes the stock resonator/collector to increase exhaust volume and simplify the flow path. The system feeds into a Helmholtz-equipped muffler engineered to control drone and deepen the exhaust note. With the valve closed, gases are routed through the muffler for a more restrained cruising sound. When the valve opens, the exhaust takes on a much freer-flowing character with substantially more volume. The complete system bolts to factory mounting locations with no cutting or welding required and includes the valve hardware needed for both pre-LCI and LCI applications.

Key Features & Specs:

• Brand: Dinan
• Product Type: Valved Cat-Back Exhaust
• Part Number: D660-0099
• Fitment: BMW X3 M40i / X4 M40i
• Chassis: G01 / G02
• Material: T304 Stainless Steel
• Body Material: T304 Stainless Steel
• Pipe Material: T304 Stainless Steel
• Construction: TIG-Welded
• System Finish: Brushed
• Tip Finish: Polished
• Tip Material: Stainless Steel
• Exhaust Tip Quantity: 4
• Tip Diameter: 3.75 in / 95mm
• Tip Style: Double-Walled, Clamp-On
• Tip Branding: Laser-Engraved Dinan Logo
• Pipe Diameter: 83mm vs. 80mm stock
• Maximum HP Gain: +6 HP at 6,600 RPM
• Maximum Torque Gain: +5 lb-ft at 6,600 RPM
• Dinan Exhaust Weight: 53 lb
• Stock Exhaust Weight: 60 lb
• Weight Reduction: 7 lb
• Factory Resonator / Collector: Removed
• Exhaust Valve: Factory valve functionality retained
• Valve Closed: Exhaust routed through muffler for more subdued operation
• Valve Open: Freer-flowing path for increased volume and sound
• Drone Control: Helmholtz-equipped muffler designed to reduce cabin resonance
• Sound: Louder, deeper exhaust note with a lower overall tone
• Pre-LCI / LCI Compatibility: Valve componentry included for both configurations
• Installation: Direct bolt-on
• Cutting Required: No
• Welding Required: No
• Mounting Hardware: Included
• Clamps Included: Yes
• Hangers Included: Yes
• Labor Time: 2.3 hours
• Grade Type: Performance
• Dinan Point Value: 3
• Emission Code: 5
• UPC: 810065215796

Fitment:

• 2018-2024 BMW X3 M40i - G01
• 2019-2025 BMW X4 M40i - G02