Dinan Free-Flow Axle-Back Exhaust – BMW M3 / M4 (F8x)

OVERVIEW

The F8x M3/M4 is an audible treat straight off the showroom floor; fitted with a Dinan exhaust it becomes even more so. Dinan's Free Flow axle-back system is built entirely from stainless steel, measured to exact specifications so it hangs from the factory hangers and mounting points, and is dyno tuned for maximum exhaust flow with minimum backpressure — giving a more aggressive sound under acceleration while reducing drone inside the car.

The computer-controlled valves are retained: they limit noise during low-speed driving and open fully under high load, and because the factory actuators and valve logic are reused, exhaust tone is still adjusted through the M-Drive settings. Gases exit through larger laser-engraved quad tips in polished stainless or ceramic black.

SPECS

• Power: +5 HP
• 100% T304 stainless steel construction
• Quad 3.5" laser-engraved tips, ceramic black coated or polished stainless
• Twin secondary exhaust valves, 76 mm diameter — 45% less restrictive than the OE valves
• Computer-controlled valve limits noise at low speed and opens fully under high load
• Stock exhaust valve actuators are reused and valve operation is unchanged, so tone is adjustable via M-Drive settings
• Drone abatement technology reduces cabin resonance
• 3 lbs lighter than the stock exhaust
• Uses the factory brackets and hangers for factory-like fitment
• Shipping weight: 56 lbs; carton approx. 50" × 34" × 12"
• Dinan published labor time: 1.8 hours
• Emissions: "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 warranty, the remainder of that warranty (typically 4 years/50,000 miles); otherwise 2 years, unlimited mileage. Wear items, maintenance services and fluids are excluded.

PARTS INCLUDED

• 1 × D663-0273A muffler assembly
• 2 × D663-0316 76 mm exhaust valve assembly
• 1 × D663-0274A hardware kit — 2 × BMW 18 30 7 620 323 fixing bows, 2 × D662-0433 valve mounts, 2 × D662-9243 2.56" Torca couplers, 6 × D671-0189 M6 oval locknuts, 6 × D671-0193 M6 socket head screws, 6 × D671-0377 M6 button head screws, 18 × M6 flat washers, 6 × M6 wave washers

TECH RESOURCES

Additional Parts Required

• None. Dinan supplies the valves, mounts, couplers and hardware needed to fit this axle-back to the factory hangers.
• Basic hand tools and secure jack stands; allow the exhaust to cool before removal. Installer-supplied.
• Optional: Dinan High Flow X-Pipe — 2015-2020 BMW M3/M4, the matching midpipe Dinan developed alongside this system.

Installation

• Dinan D660-0050 / D660-0050-BLK Free Flow Axle-Back Exhaust installation instructions (PDF) — INS660-0050: bill of materials, valve assembly, hanger and clamp positions and tip alignment.

Notes

• 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.
• Tip finish is selected by part number — check the variant you are ordering. Confirm fitment for your specific build with Speed Logic before ordering.

PART NUMBER

• D660-0050 — polished stainless laser-engraved tips
• D660-0050-BLK — ceramic black coated laser-engraved tips

VEHICLE APPLICATIONS