Dinan Free Flow Axle-Back Exhaust System with Black Tips for BMW M340i / M440i 2020-2024

Dinan's free-flow axle-back (D660-0085-BLK) is the black-ceramic-tip kit for G20 M340i and G22 / G23 / G26 M440i cars. Four 4-inch (102 mm) double-walled, clamp-on black ceramic tips, laser-engraved and straight-cut, fill the factory bumper openings. Upstream, 76 mm T304 stainless piping replaces the stock 70 mm tubes. Dinan rates the change at plus 6 horsepower and plus 5 lb-ft of torque at 6,600 rpm, and the assembly is roughly 4 pounds lighter than the original rear section.

Because a quad-tip layout cannot copy the factory trick of shutting one outlet, Dinan adds a second valve and actuator opposite the stock unit and enlarges both valves to 76 mm. Closed, the system dumps everything through the muffler and the inner tips; open, the outer pipes flow for a deeper, straighter note. The original actuator is reused so M-Drive still decides when that happens. The rest of the system is TIG welded and brush finished, with the darker ceramic tips as the visible difference from polished D660-0085. Dinan lists labor at 2.5 hours.

Dinan titles the part for BMW M340i / M440i on G20 / G22 / G23 / G26 and, matching the polished sibling and the 20-24 application, covers B58 M340i sedans plus M440i coupe, convertible, and Gran Coupe cars through 2024. It is not for 330i / 430i, M3 / M4, or later LCI G20 / G22 models. The polished-tip sibling remains a separate SKU and is not merged here.

Emission code 5 applies. The packaged kit ships at 53.4 x 25 x 11.8 inches and 69.4 pounds (UPC 813725028774). Coverage follows Dinan's standard limited warranty: the remainder of the vehicle factory limited warranty (up to 4 years / 50,000 miles) or 2 years / unlimited miles, whichever is greater. The later DNN-prefixed listing shares this part number and redirects here.

Features

• Free-flow axle-back exhaust for G20 M340i and G22 / G23 / G26 M440i
• Plus 6 horsepower and plus 5 lb-ft of torque at 6,600 rpm
• Quad 4-inch (102 mm) black ceramic, double-walled, clamp-on, laser-engraved tips
• 76 mm piping versus the factory 70 mm; about 4 lb lighter than stock
• Second 76 mm valve and actuator added so both banks flow evenly

What's Included

• Dinan Free Flow Axle-Back Exhaust (D660-0085-BLK)

Specifications

Questions about fitment? Call (310) 231-0292 or text (310) 886-3111.

Fitment Notes

• For 2020-2024 BMW M340i (G20) and 2021-2024 M440i coupe (G22), convertible (G23), and Gran Coupe (G26), including xDrive. Dinan specifies G20 / G22 / G23 / G26 for this SKU.
• Not for 330i / 430i, M3 / M4, or 2025-up LCI G20 / G22 models.
• The polished-tip sibling is D660-0085.