An X3M or X4M runs the same S58 you find in the M3 and M4. From the driver's seat, the factory exhaust does a good job of hiding that fact. Heavy SUV muffling, a narrow tone, and tips that look small in that wide rear valance. If you bought the fast one, it should sound like the fast one.
The Dinan Free Flow Axle-Back Exhaust for the BMW F97 X3M and F98 X4M swaps the factory rear section for 76mm T304 stainless tubing, 76mm valves that are 30% less restrictive than stock, and quad 4.5 in. black ceramic tips. Dinan measured +8 HP and +6 lb-ft at 6600 RPM, and the system is 5 lbs lighter than the factory part.
How the Dinan X3M Axle-Back Exhaust Sounds and Flows
Dinan kept the factory computer-controlled exhaust valves. That matters. At low speed and light load the valves stay closed and the car stays livable, so you are not droning down the freeway on a family trip. Put your foot down and the valves open, and the larger tubing lets the S58 breathe with what Dinan describes as a deeper, fuller tone that mimics a straight pipe.
The system is 100% T304 stainless steel, TIG welded with a brushed finish. The four 4.5 in. clamp-on tips carry a black ceramic coating and a laser-engraved Dinan logo, and they fill the factory tip cutouts with a proper M-car presence.
Axle-Back Exhaust Install and Legal Status
No cutting and no coding. It is a bolt-on axle-back that uses the factory mounting points, with a Dinan-quoted labor time of 2.5 hours. Dinan states it is legal for sale or use on emissions-controlled vehicles because it does not affect vehicle emissions. Dinan part number D660-0086-BLK. Sold by AutoTecknic, an authorized Dinan dealer.
What's Included
- Dinan Free Flow axle-back exhaust with 76mm valves
- Quad 4.5 in. black ceramic laser-engraved clamp-on tips
- Mounting hardware and band clamps
Key Features
- Dinan-tested +8 HP and +6 lb-ft at 6600 RPM
- 76mm tubing vs 70mm stock
- 76mm exhaust valves, 30% less restrictive than factory
- Factory computer-controlled valve operation retained
- 100% T304 stainless steel, TIG welded, brushed finish
- Quad 4.5 in. black ceramic tips with laser-engraved Dinan logo
- 5 lbs lighter than stock (72 lbs)
- Bolt-on install, about 2.5 hours
Vehicle Fitment
Fits the following S58-powered BMW M models:
- BMW X3M / F97 (2020-2025): X3M, X3M Competition
- BMW X4M / F98 (2020-2025): X4M, X4M Competition
This part is listed only for the F97 X3M and F98 X4M. It is not listed for the X3 M40i or X4 M40i.
Installation Notes
This is a straightforward bolt-on job for a shop or an experienced DIYer with a lift. Budget about 2.5 hours and a second pair of hands, since the full assembly weighs 72 lbs. Follow the Dinan instructions included with the kit.
- Let the exhaust cool completely and raise the vehicle safely.
- Disconnect the factory exhaust valve actuators and loosen the clamp ahead of the rear section.
- Support the factory rear section, release it from the hangers and remove it.
- Fit the Dinan axle-back to the factory mounting points and connect it with the supplied band clamps, transferring the valve actuators as directed.
- Install and align the quad tips, torque all clamps, reconnect the actuators and check for leaks and correct valve operation with the engine running.
