Dinan Free-Flow Axle-Back Exhaust – BMW 340i / 440i (F30/F32)

OVERVIEW

Dinan engineers designed this axle-back system for the F30 340i and F32 440i to improve exhaust flow by reducing back pressure, raising power output and delivering a sporty note that is civilized when you want it to be and pleasantly aggressive under hard acceleration. The tone is not the only thing that improves — the additional burbles and pops that come with it are part of the appeal. A Helmholtz chamber design cancels the low-RPM resonance, or drone, that usually accompanies a freer-flowing system.

The system is built to exacting specifications and uses the factory hangers, so it fits like an OE part. It is made entirely from 16-gauge 304 stainless steel and will resist corrosion for years to come. Twin 89mm (3.5 in) laser-engraved tips in polished stainless or ceramic black finish the look, and the factory computer-controlled exhaust valve is eliminated.

SPECS

• More power: +6 HP @ 6600 RPM and +5 lb-ft @ 6600 RPM
• Helmholtz chamber design to reduce low-RPM drone
• 100% 16-gauge T304 stainless steel construction
• Twin 89mm (3.5 in) laser-engraved tips, polished stainless or ceramic black finish
• Mounts to the factory brackets and hangers; clamps and hangers included
• The factory computer-controlled exhaust valve is eliminated
• Dinan published installation labor: 1.2 hours
• Weight: 45 lb
• Dinan emissions statement: “This part is legal for sale or use on Emissions Controlled Vehicles, Uncontrolled (Non-Emissions Controlled) Vehicles, and Racing Use Only Vehicles because it does not affect vehicle emissions and is not covered by emissions regulations.”
• Dinan warranty: on a vehicle still covered by the BMW new-car limited warranty (4 years/50,000 miles), Dinan products are warranted for the remaining term of that warranty; otherwise Dinan Performance Products carry a 2-year, unlimited-mileage warranty from the date of original purchase. Wear and maintenance items — friction materials, filters, fluids, spark plugs, drive belts and bulbs — are excluded.

PARTS INCLUDED

• Complete axle-back muffler assembly as supplied by Dinan, with the clamps and hangers needed to fit it.
• The factory muffler hangers are transferred from the stock mufflers to the Dinan mufflers during installation.
• See the Dinan installation instructions for the full bill of materials.

TECH RESOURCES

Additional Parts Required

• None. Dinan specifies no additional hardware for this part — the clamps and hangers are supplied.
• Optional pairing: the Dinan High Flow Mid-Pipe (D660-0057) removes both factory resonators ahead of this muffler for a more aggressive tone.
• Installer-supplied tools and consumables: vehicle lift or jack stands, standard hand tools and penetrating oil for the factory clamp hardware.

Installation

• Dinan High Performance Muffler installation instructions (Rev 03/28/19), covering D660-0055 and -BLK: Download PDF

Notes

• Years reflect the 2016–2020 application range Dinan publishes for D660-0055. The installation document is shared across several Dinan muffler part numbers; F33 Convertible and F36 Gran Coupe cars take a different Dinan part number.

PART NUMBER

• D660-0055 — polished stainless tips
• D660-0055-BLK — ceramic black tips

VEHICLE APPLICATIONS