The Dinan Valved Cat-Back Exhaust for the G01 X3 M40i and G02 X4 M40i replaces the factory single-to-dual layout with an enlarged, straight, single-pipe design in 100% T304 stainless steel. Eliminating the central collector and resonator raises volume, while a Helmholtz-equipped muffler limits drone frequencies for the signature low Dinan rumble. Retained factory valve control lets the exhaust shift from refined cruising to rowdy at full throttle, and it accepts an optional valve remote for on-demand sound. The bolt-on system needs no cutting or welding, ships with valve componentry for both pre-LCI and LCI cars, saves 7 pounds over stock, and adds up to +6 HP and +5 lb-ft. Quad 3.75-inch (95mm) double-walled tips are laser engraved with the Dinan logo.
Specifications
| Type | Valved cat-back exhaust |
| Position | Cat-back (full system aft of catalysts) |
| Material | 100% T304 stainless steel |
| Tubing Diameter | 83mm (vs 80mm stock) |
| Muffler | Helmholtz-equipped, drone abatement |
| Tips | Quad 3.75in (95mm) double-walled clamp-on, laser-engraved Dinan logo |
| Tip Finish | Black ceramic coated |
| Fitment Note | Includes pre-LCI and LCI valve componentry |
| Power Gain | +6 HP / +5 lb-ft (max) |
| Weight Savings | 7 lb lighter (53 lb vs 60 lb stock) |
| Part Number | D660-0099-BLK |
Documents: Installation Instructions (PDF)
This part fits:
| Year | Make | Model | Submodel |
|---|---|---|---|
| 2018-2024 | BMW | X3 | M40i |
| 2019-2025 | BMW | X4 | M40i |
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
