The Dinan Free Flow Axle-Back Exhaust is built entirely from TIG-welded, brushed T304 stainless steel and runs larger 76mm tubing versus the 70mm stock piping for freer flow. A dual-valve design adds a second 76mm computer-controlled valve so gas flows evenly regardless of valve position, with valves roughly 30% less restrictive than the OE units that open under load for an aggressive, near straight-pipe tone and close at low speed for a civil cabin. Quad 4in double-walled, black ceramic-coated, laser-engraved tips finish the system. Dinan rates gains of +6 HP and +5 lb-ft at 6600 RPM, and the system is about 4 lbs lighter than stock. Installation is bolt-on with the included mounting hardware.
Specifications
| Type | Free Flow axle-back exhaust (dual-valve) |
| Material | T304 stainless steel, TIG welded, brushed |
| Tips | Quad 4in double-walled, laser-engraved |
| Finish | Black ceramic-coated tips |
| Valves | Dual 76mm computer-controlled (30% less restrictive than OE) |
| Piping Diameter | 76mm (vs 70mm stock) |
| Power Gain | +6 HP & +5 lb-ft @ 6600 RPM |
| Part Number | D660-0085-BLK |
Documents: Installation Instructions (PDF)
This part fits:
| Year | Make | Model | Submodel |
|---|---|---|---|
| 2020-2026 | BMW | M340i | Base |
| 2020-2026 | BMW | M340i xDrive | Base |
| 2021-2026 | BMW | M440i | Base |
| 2022-2024 | BMW | M440i Gran Coupe | Base |
| 2021-2024 | BMW | M440i xDrive | Base |
| 2022-2024 | BMW | M440i xDrive Gran Coupe | Base |
Shipping
- Orders placed before 3 PM ET typically ship the same business day. Larger items ship within 1 to 3 business days.
- Standard, expedited, and overnight options at checkout.
- Oversized items ship by freight and take longer.
- Special order items follow a lead time we confirm with you individually before the order is committed.
- Backordered items ship as soon as stock lands. Lead times are manufacturer estimates and can change. Contact us for current ETAs.
- Need to cancel? Email us right away. Cancellations are not guaranteed once an order is in process. In-stock orders cancel free before they ship; a 6% fee applies only to confirmed backorders and special orders.
- International orders: prices do not include VAT, duties, or import fees. Your country charges these at import and they are the buyer’s responsibility.
Returns
- 30 days from delivery to request and ship back a return on new, uninstalled items in original packaging with all hardware.
- Standard returns: 8% restocking fee on the item price before tax and shipping. Shipping is not refunded in either direction. All waived if the item is defective or we made the error.
- Fitment guaranteed: select your vehicle above, or confirm fitment with us in writing before you order. If the part shows as a fit and it is wrong, the return is on us, even after installation. Otherwise, installed or used parts cannot be returned.
- Final sale: special orders, coilovers, electronics, engine internals, turbochargers, superchargers and turbo kits, unless defective or we sent the wrong item.
- Product images may be representative. The SKU and specifications in the listing are what ships.
- Email us for return authorization before shipping anything back.
Full details: Shipping Policy · Returns & Refunds · Warranty
