The B58 in your M240i is one of the best-sounding engines BMW sells right now. The factory exhaust keeps most of that sound to itself. It runs a single valve on one side, so even when it opens, flow and tone are not balanced across the back of the car.
The Dinan Valved Axle-Back Exhaust for the BMW G42 M240i fixes both. It keeps the factory valve, adds a matching second one, and steps the piping up from 70mm to 76mm. The result is a deeper, fuller tone from four 4-inch polished tips, a Dinan-tested 6 HP and 5 lb-ft at 6,600 RPM, and a system that weighs 4 lb less than stock.
How the Dinan Valved Axle-Back Exhaust Stays Civil
You do not have to give up a quiet cold start or a calm commute. The computer-controlled valves are retained, so they stay closed and limit noise at low speed, then open under load for the full sound. Both valves are 76mm, which Dinan rates as 30% less restrictive than the OE valves, and because there is one on each side, flow and sound are symmetrical once they open.
Construction is TIG-welded, brushed T304 stainless steel. The quad tips are 4-inch, double-walled, polished and laser engraved, and they clamp on for easy alignment. Dinan part number D660-0098. Sold by AutoTecknic, an authorized Dinan dealer.
Is the Dinan M240i Exhaust Street Legal?
Yes. It is an axle-back, so it sits behind the catalytic converters and does not affect emissions. Dinan lists it as legal for sale or use on emissions-controlled vehicles. No tune is listed as required by Dinan. Local noise rules still apply.
What's Included
- Dinan T304 stainless steel valved axle-back exhaust
- Second 76mm exhaust valve and actuator
- Quad 4-inch polished, laser-engraved clamp-on tips
- Mounting hardware and clamps
Key Features
- Dinan-tested +6 HP and +5 lb-ft at 6,600 RPM
- 76mm piping vs 70mm stock
- Twin 76mm valves, 30% less restrictive than OE
- Factory valve actuator reused, second valve added for symmetrical flow
- Quad 4-inch double-walled, polished, laser-engraved tips
- TIG-welded, brushed T304 stainless steel
- 4 lb lighter than the stock system
- About 2.5 hours to install
Vehicle Fitment
Fits the following B58-powered BMW 2 Series Coupe models:
- BMW 2 Series / G42 Coupe (2022-2026): M240i xDrive
- BMW 2 Series / G42 Coupe (2023-2026): M240i
Not for the 230i.
Installation Notes
This is a bolt-on axle-back, but the added valve makes it more involved than a simple muffler swap. Dinan rates it at about 2.5 hours. A lift makes it much easier. Follow the Dinan instructions included with the kit.
- Safely raise and support the car and let the exhaust cool completely.
- Unplug the factory valve actuator and remove the factory rear muffler section from its hangers.
- Transfer the factory actuator to the Dinan system and install the second Dinan valve and actuator as directed.
- Hang the Dinan axle-back on the factory mounts with the supplied hardware, then fit and align the clamp-on tips.
- Tighten all clamps, reconnect the actuators, start the car and confirm both valves open and close with no warning lights.
