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.
| 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: In-stock orders placed before 3 PM EST ship the same day, and everything else ships within 24 hours. Standard, expedited, and overnight options are available at checkout. Backordered items ship as soon as we get them back in stock. Contact us for lead times. See the full Shipping Policy.
Returns: 30-day returns on new, unused items in original packaging. See the full Refund Policy.
