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MAD

S58 4" Fat Boy Single Midpipe

Name: S58 4" Fat Boy Single Midpipe
Brand: MAD
SKU: MAD-124

$849.00 $648.93 Save $200.07

SKU: MAD-124

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Non-Returnable Item

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Moderate — 2–4 hours

Overview

The MAD BMW S58 4" Fat Boy Single Midpipe is an exhaust component designed to maximize performance and sound for the G8X M3/M4 platform. It features a full-length single 4" center section with a minimum pipe diameter of 3" throughout to maintain optimal exhaust flow.

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The MAD BMW S58 4" Fat Boy Single Midpipe is engineered to deliver enhanced exhaust flow and a more aggressive sound for the G8X M3/M4 platform. This component is designed to maximize performance and sound without compromise, featuring a full-length single 4" center section. This midpipe maintains optimal exhaust flow from front to back with a minimum pipe diameter of 3" throughout its length. The FATBOY Midpipe aims to transform the vehicle's character, offering a balance of refined aggression for both street and track applications. Key features include a full-length single 4" center section and a minimum 3" diameter throughout for consistent flow. It comes with 3" and 2.75" reducer couplers, allowing connection to 3" aftermarket axle-back systems or factory axle-back systems.

Product descriptions are provided by our supplier partners and may not always be perfectly accurate. Not sure this fits? or call (760) 282-4645 and we’ll verify before you order.

Fitment

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Specifications

Brand	MAD
Part Number	MAD-124
Category	Exhaust

Videos

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Returns & Fitment

Built for enthusiasts. Every order is backed by our 30 day return window on eligible items. Unused and uninstalled products may be returned with approved RMA and no restocking fees when received in new condition. Orders placed through the MOTORMIA app with a complete build qualify for our Fitment Guarantee — free return shipping if the part doesn’t fit your exact setup. The guarantee covers fit only; installation must follow manufacturer instructions, and we recommend a qualified shop for parts marked Difficulty 4–5.

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Shipping

Orders are processed in 1–3 business days. In stock parts ship promptly from our partner network. Special-order items either aren’t currently stocked or are built to your spec — expect 4–6 weeks. If a part goes on backorder while your order is in the queue, we’ll reach out and work through discounted alternatives together.

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