An X3 M or X4 M 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 X3 M and F98 X4 M 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 X3 M 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 X3 M / F97 (2020-2025): X3 M, X3 M Competition
  • BMW X4 M / F98 (2020-2025): X4 M, X4 M Competition

This part is listed only for the F97 X3 M and F98 X4 M. 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.

  1. Let the exhaust cool completely and raise the vehicle safely.
  2. Disconnect the factory exhaust valve actuators and loosen the clamp ahead of the rear section.
  3. Support the factory rear section, release it from the hangers and remove it.
  4. Fit the Dinan axle-back to the factory mounting points and connect it with the supplied band clamps, transferring the valve actuators as directed.
  5. Install and align the quad tips, torque all clamps, reconnect the actuators and check for leaks and correct valve operation with the engine running.