$476.00 USD
$476.00 USD






SKU: MAD-136
$659.00
Out of Stock - Available January 14th, 2026
Transform your BMW G87 M2's exhaust performance with the MAD S58 4" Fat Boy Single Midpipe. Engineered for the high-revving S58 engine, this midpipe delivers unrestricted flow, sharper throttle response, and an intoxicating, deep, aggressive tone that turns heads on the street or track. Say goodbye to rasp and hello to pure power.
Built for enthusiasts who demand the best, the Fat Boy Midpipe optimizes every aspect of your BMW M2 G87 exhaust system.
Whether you're tuning for more horsepower or just crave that signature BMW growl, the MAD Fat Boy Midpipe is your gateway to elevated driving dynamics.
Yes, it's designed exclusively for the S58-powered G87 M2 platform and works with both OEM and aftermarket downpipes.
It produces a deeper, more aggressive tone with less interior rasp, enhancing the overall auditory experience without drone.
The midpipe, 3" and 2.75" reducer couplers, upgraded brace, and all necessary clamps for installation.
No, it's a direct bolt-on using factory points, but we recommend a certified mechanic for best results.
Expected availability: January 14th, 2026. Sign up for notifications to be the first to know!
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$476.00 USD
$476.00 USD
This product can expose you to chemicals such as lead and lead compounds, which are known to the State of California to cause cancer or birth defects or other reproductive harm. For more information, visit www.P65Warnings.ca.gov.
For a complete list of chemicals known to cause harm, visit https://www.p65warnings.ca.gov/chemicals.
Under the federal Clean Air Act (42 U.S.C. §7522(a)(3)), it is illegal to manufacture, sell, install, or use any part that defeats or alters a motor vehicle’s emission control system for use on public roads. Unless a product has received an Executive Order (EO) from the California Air Resources Board (CARB), it is not legal for use or installation on any pollution-controlled vehicle driven on public highways.
Some states have CARB-equivalent or independent emissions laws. Customers are responsible for verifying local regulations before purchasing or installing emissions-related products.
All performance, racing, or competition parts sold by this company are intended solely for off-road, closed-course, or competition use on vehicles that are never registered or used on public highways.
Kies Motorsports, LLC sells and markets these products for lawful use only. We do not condone or authorize the use of emission-control defeat devices or any modification that violates the Clean Air Act or state regulations.