The ARM S58 Midpipe upgrade is engineered to unlock the aggressive exhaust character of your G80 M3 or G82 M4. By removing the secondary catalytic converters and the two center resonators, this midpipe significantly enhances the sound of your S58-powered BMW. At the same time, it retains the factory muffler, so you can still control the exhaust valves—keeping them closed for a quieter, refined tone or opening them for maximum volume and performance sound.
Enhance the Sound of Your S58
The ARM S58 Midpipe not only increases overall exhaust volume but also transforms the tone into something far more distinctive than a standard G80 M3. It also makes the signature exhaust burbles more noticeable, even with the factory tune.
The G82 M4 featured in the video below is equipped with both the ARM S58 Midpipe and ARM S58 Downpipes. When paired together, the midpipes and downpipes deliver an even louder and more aggressive exhaust note compared to running the midpipe alone.
Highlights
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Exotic exhaust sound
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X-pipe design
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Compatible with OEM underbody brace
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3-inch piping design
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Constructed from SS304 stainless steel
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Reduces weight by approximately 15 lbs compared to OEM
The ARM S58 Midpipes are a
3" designfrom the downpipe connection all the way to the rear section where it will reduce to 2.75" to perfectly connect to the OEM muffler section. The ARM S58 Midpipes start with a
OEM-style 2-Bolt flange which can mate up to either the OEM downpipes, or upgraded downpipes that fit the OEM exhaust
. These flanges will accommodate the OEM midpipe gasket perfectly. Alternatively, you can choose to upgrade your S58's crossover pipe with the ARM S58 Crossover Pipe.
The optional ARM S58 Crossover Pipe replaces the heavy OEM pipe to open up more sound and saves an additional 4lbs.

The ARM S58 Midpipe then transitions to the X-Pipe section of the exhaust via the slip-fit connections on either side. The X-Pipe is the heart of the ARM S58 Midpipe and is where the magic happens. The sound waves of each bank of your S58 engine are combined to produce a much more exotic and richer exhaust note. The X-Pipe section lives above the OEM brace with ample clearance, there is no need to install a larger brace.
Explore Aftermarket Parts Collection For G8X S58 VehiclesFrom the X-Pipe section the ARM S58 Midpipe upgrade transitions back to the OEM muffler, which allows full use of the OEM exhaust valves.
This gives you the freedom to choose between open and closed exhaust flaps, controlling the volume your G80 M3/M4 produces. To get a look to match your ARM S58 Midpipe check out the ARM S58 Exhaust Tips.

The ARM S58 Midpipe will secure to the
exhaust hanger on the driver's side using a standard exhaust hanger prong. It is secured to the passenger's side using the
OEM style mounting bracket. These help the exhaust from jostling around during aggressive driving.
IN THE BOX
• 1x ARM S58 Crossover Pipe (Optional)
• 2x Front Midpipe Sections
• 1x X-Pipe
• 4x Clamps
FITMENT GUIDE
| Make |
Model |
Submodel |
Engine |
| BMW |
G80 |
M3 |
S58 3.0L |
| BMW |
G80 |
M3 Competition xDrive |
S58 3.0L |
| BMW |
G82 |
M4 |
S58 3.0L |
| BMW |
G82 |
M4 Competition xDrive |
S58 3.0L |
| BMW |
G83 |
M4 |
S58 3.0L |
| BMW |
G83 |
M4 Competition xDrive |
S58 3.0L |
ARM MOTORSPORTS LIFETIME WARRANTY
Every ARM Motorsports product is backed by a lifetime warranty which is automatically issued at the time of purchase. Your warranty protects you against any defects in craftsmanship or fitment. The warranty entitles you to a replacement unit.
This product is for Off-Road Use Only. Items sold for off-road use only are illegal to use on public roads in most states and provinces. This product is intended for racing vehicles which may never be used on a public road.