The M550i is a twin-turbo V8 sport sedan that spends most of its time pretending to be a quiet executive car. That is great on a Monday commute. It is less great when you are on an empty on-ramp and the V8 sounds like it is behind a closed door.
The Dinan Free Flow Axle-Back Exhaust for the BMW G30 M550i xDrive lets the V8 speak up without turning the car into something it is not. It is 100% 304 stainless steel, keeps the factory computer-controlled valves, and finishes in quad 4 in. double-walled, laser-engraved black ceramic tips. On Dinan's dyno it adds 8 HP and 6 lb-ft at 6,600 RPM.
Dinan M550i Axle-Back Exhaust: Louder When You Want It
The factory valves stay in charge. At low speed they limit noise, so the car stays composed in traffic and at highway cruise. Under high load they open fully and the V8 gets a free-flowing path out the back, which is where Dinan measured the gain. Valve logic is unchanged, so there is no coding and no tune. For more sound, Dinan's High Flow Middle Exhaust is confirmed to fit with this axle-back.
Install and Legal Status
It is a bolt-on install with about 1.9 hours of labor, using the factory mounting points. The complete system weighs 73 lbs. Because it sits behind the catalytic converters and does not affect emissions, Dinan lists it as legal for sale and use on emissions-controlled vehicles in all 50 states. Dinan part number D660-0075-BLK. Sold by AutoTecknic, an authorized Dinan dealer.
What's Included
- Dinan 304 stainless steel valved axle-back exhaust
- Quad 4 in. double-walled black ceramic clamp-on exhaust tips
- Installation hardware
Key Features
- Dinan-tested +8 HP and +6 lb-ft at 6,600 RPM
- Retains factory computer-controlled exhaust valves
- Quiet at low speed, fully open under high load
- 100% 304 stainless steel construction
- Quad 4 in. double-walled, laser-engraved black ceramic tips
- Bolt-on install, about 1.9 hours, no coding or tune required
- Emissions legal in all 50 states (does not affect emissions)
Vehicle Fitment
Fits the V8-powered BMW 5 Series:
- BMW 5 Series / G30 Sedan (2018-2023): M550i xDrive
Installation Notes
A DIYer with a lift or solid jack stands can do this, and a shop will have it done in about 1.9 hours. The system is heavy at 73 lbs, so have a second person help lift it into place. Let the exhaust cool completely first.
- Raise and support the car and let the exhaust cool fully.
- Unplug the factory valve actuators and loosen the clamps ahead of the rear mufflers.
- Unhook the hangers and remove the factory rear section.
- Hang the Dinan axle-back, fit and reconnect the factory valve actuators.
- Fit and align the clamp-on tips, tighten all hardware, then start the car and check for leaks and valve operation.
