Dinan Free Flow Axle-Back Exhaust for 2016-18 340i, 2017-20 440i - D660-0055-BLK

Add a sharper exhaust character to your turbocharged BMW with the Dinan D660-0055-BLK Free Flow Axle-Back Exhaust. Built for select 2016-2020 BMW 340i and 440i applications, this single-in/dual-out system combines 16-gauge T304 stainless steel construction with a chambered muffler, integrated Helmholtz chamber, and twin 3.5-inch black ceramic coated exhaust tips. Dinan designed the system to reduce backpressure and improve exhaust flow, with stated gains of 6 HP and 5 lb-ft of torque at 6,600 RPM.

Sound tuning is a major part of the D660-0055-BLK design. Under acceleration, the exhaust delivers a stronger performance tone with more noticeable burbles and pops, while the Helmholtz chamber helps suppress unwanted low-RPM resonance during everyday driving. The system uses a 3.25-inch intermediate pipe feeding a single-inlet/dual-outlet muffler with 2.75-inch tailpipes, and installs using the factory brackets and hangers. This configuration eliminates the factory computer-controlled exhaust valve.

Key Features & Specs:

• Brand: Dinan
• Series: Free Flow
• Product Type: Axle-Back Exhaust
• Part Number: D660-0055-BLK
• Fitment: BMW 340i / 340i xDrive / 440i / 440i xDrive
• Chassis: F30 / F32
• System Style: Rear Axle-Back
• Exhaust Configuration: Single In / Dual Out
• Exit Location: Split Rear
• Material: T304 / 304 Stainless Steel
• Body Material: 16-Gauge T304 Stainless Steel
• Pipe Material: T304 Stainless Steel
• System Finish: Brushed
• Intermediate Pipe Diameter: 3.25 in
• Tailpipe Diameter: 2.75 in
• Muffler Included: Yes
• Muffler Quantity: 1
• Muffler Configuration: Single Inlet / Dual Outlet
• Muffler Style: Chambered
• Muffler Material: 304 Stainless Steel
• Tip Finish: Black Ceramic Coated
• Exhaust Tip Quantity: 2
• Tip Diameter: 89mm / 3.5 in
• Tip Shape: Round
• Tip Cut: Straight
• Tip Branding: Laser-Engraved Dinan Logo
• Maximum HP Gain: +6 HP at 6,600 RPM
• Maximum Torque Gain: +5 lb-ft at 6,600 RPM
• Drone Control: Integrated Helmholtz chamber
• Sound: Sportier exhaust tone with additional burbles and pops
• Factory Exhaust Valve: Eliminated
• Catalytic Converters Included: No
• Installation: Uses factory brackets and hangers
• Hardware Included: Yes
• Clamps Included: Yes
• Hangers Included: Yes
• Labor Time: 1.2 hours
• Length: 48 in
• Width: 30 in
• Height: 11 in
• Weight: 45 lb
• Grade Type: Performance
• Dinan Point Value: 3
• Emission Code: 5
• UPC: 813725023199

Fitment:

• 2016-2018 BMW 340i - F30
• 2016-2018 BMW 340i xDrive - F30
• 2017-2020 BMW 440i - F32
• 2017-2020 BMW 440i xDrive - F32