The B58 turbo six-cylinder is one of BMW’s best sounding engines, and that’s saying a lot. BMW engines in the turbo era haven’t exactly been known for their exhaust notes, with one notable exception being the N55 turbo six which debuted back in 2009. The B58 began replacing this engine in 2016, and it has managed to do what few expected; improve upon the sound of its predecessor. The most potent version of the B58 didn’t arrive until a few years into production, and this 380-horsepower variant is used on models like the Z4 M40i and M340i.
The BMW B58M30O1, as it is known, sounds quite good when exhaling through the factory exhaust on any of BMW’s current M Performance models, and adding a dealer-installed M Performance exhaust system improves things nicely. Announced earlier this month however, BMW CCA sponsor Dinan‘s new M340i axle-back system elevates things to a new realm.
First off, there are the obvious quad tips. Typically reserved exclusively for M cars, and a great way to distinguish one out on the road, Dinan’s new system brings the signature look to the M Performance model range. Offended by the four pipes? The M340i’s performance speaks for itself, with acceleration that’s on par with the outgoing F80 M3. Both black and polished stainless steel tips are available, and the system retains use of the original valve actuator while adding another setup to promote even flow of exhaust gases.
If you’re into the look of convention exhaust pipes over the new bumper-mounted frames many cars (including the M340i) are now using, the Dinan axle-back system is a great upgrade to achieve the more traditional appearance. The improvements go beyond visuals and sound though, as Dinan’s press release explains:
- More Power: max gains of six horsepower at 6,600 rpm, five pound-feet at 6,600 rpm.
- Quad 4-inch diameter clamp-on, double-walled laser engraved exhaust tips. Available in ceramic black or polished.
- 100% 304 stainless steel construction.
- Larger diameter piping for increased flow (76mm as opposed to 70mm).
- Four pounds lighter than the stock system.
- Stock exhaust valve actuator reused and another valve and actuator added to the opposing side promoting even flow regardless of valve position.
- Computer -controlled exhaust valves are retained and limit noise during low speed driving and open fully during high-load conditions.
- Twin exhaust valves are a whopping 76mm diameter, making them 30% less restrictive than the OE valves.
- Easy bolt-on installation with included mounting hardware.
Of course, the whole idea behind upgrading your exhaust is better sound. While welding in a Y-pipe and flashing a quality tune on something like one of BMW’s modern turbocharged six-cylinder engines makes for truly raucous noise, complete with pops, burbles, and loud cracks upon downshift, Dinan’s system strikes a great balance between being not over the top, and opening things up nicely when the driver happens upon a good road.
Check out the video below and judge for yourself.—Alex Tock
DINAN FREE FLOW AXLE-BACK EXHAUST – 2019–2020 BMW M340i – Black Tips
DINAN FREE FLOW AXLE-BACK EXHAUST – 2019–2020 BMW M340i – Polished Stainless Steel Tips
[Photos and video courtesy Dinan Cars.]