Exhaust› Exhaust Pipes, Systems and Components

ARM

S58 4.5" Single Midpipe

$997.00

SKU: S58MID

In Stock
In Stock
Ships by Sep 12
Free Shipping over $200
$100 Minimum Order
30 Days Return
INSTALL DIFFICULTY
DIY PRO SHOP

Moderate — 2–4 hours

Overview

The ARM S58 4.5" Single Midpipe is an exhaust upgrade designed for BMW G8X M3/M4 models. It aims to unleash a more exotic exhaust sound by removing secondary catalysts and two middle resonators. This midpipe connects to the OEM muffler, retaining the use of exhaust valves for adjustable sound levels.
Show original supplier description
The ARM S58 4.5" Single Midpipe is engineered to enhance the exhaust sound of your S58-powered BMW G8X M3/M4. This upgrade removes the secondary catalysts and two middle resonators, significantly improving the exhaust note to be deeper, richer, and more audible, even with OEM tuning. By retaining the OEM muffler, you maintain full control over the exhaust valves, allowing you to switch between a subtle tone and maximum volume. Constructed from SS304 stainless steel, the midpipe features a massive 4.5" design from the downpipe connection, reducing to 2.75" to mate with the OEM muffler. It utilizes an OEM-style 2-bolt flange compatible with stock or upgraded downpipes. The slip-fit connections and a unique merging section combine the sound waves from each engine bank for a distinctive tone. An OEM-style mounting bracket secures the midpipe during aggressive driving. This product is for Off-Road Use Only and is intended for racing vehicles. The ARM S58 Midpipe is designed for the BMW G80 M3, G80 M3 Competition xDrive, G82 M4, G82 M4 Competition xDrive, G83 M4, and G83 M4 Competition xDrive, all equipped with the S58 3.0L engine. It also includes ARM Downpipe Gaskets, an ARM Extended Brace, and ARM Clamps in the box. ARM Motorsports backs this product with a lifetime warranty against defects in craftsmanship or fitment.

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

BrandARM
Part NumberS58MID
CategoryExhaust

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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.

Free shipping over $200 in the continental US. Alaska, Hawaii, U.S. territories (Puerto Rico, U.S. Virgin Islands, Guam, American Samoa, and the Northern Mariana Islands), and international orders carry surcharges — most appear at checkout. Some exceptions (LTL freight, or suppliers who quote freight only after we place the order) won’t. In those cases we’ll reach out with the exact charge before your order moves forward.

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