Exhaust› Exhaust Pipes, Systems and Components

MAD MAD

B58 Catted Downpipe with 200 CEL Cat

$369.00

SKU: MAD-056

In Stock
In Stock
Ships by Sep 13
Free Shipping over $200
$100 Minimum Order
30 Days Return
INSTALL DIFFICULTY
DIY PRO SHOP

Moderate — 2–4 hours

Overview

The MAD B58 Catted Downpipe is an exhaust upgrade designed for BMW F and G chassis vehicles, as well as the Toyota Supra. Constructed from 304 stainless steel, it features a 200 CEL high-flow catalytic converter and a flex section. This downpipe aims to improve airflow, increase horsepower, and enhance exhaust sound.
Show original supplier description
The MAD B58 4.5" Catted Downpipe is engineered to replace the stock downpipe on select BMW B58-powered vehicles and the Toyota Supra, aiming to maximize airflow and performance. Crafted from premium 304 stainless steel, it incorporates a 200-cell high-flow catalytic converter and a flex section designed to reduce stress and vibration from engine movement and heat. It is compatible with both right-hand drive and left-hand drive vehicles. The manufacturer claims an increase of up to 30HP on stock turbos, with potential for more on upgraded turbo setups. Fitment includes a range of BMW models such as the M240i, 340i, M340i, 440i, 540i, 640 GT, 740i, X3 M40i, X4 M40i, X5 40i (Non-LCI), X6 40I (Non-LCI), X7 40i (Non-LCI), Z4 M40i, and the 2019+ Toyota Supra 3.0L. It's important to note that the M340i models from 2020-2024 do not fit 2025 models, and certain X5, X6, and X7 models are specified as 'Non LCI only'. A gasket is not included and part #18328612538 is required for installation. Emissions Disclaimer: This product is not legal for sale or use on pollution-controlled vehicles operated on public roads, highways, or streets. It is intended for off-road, race, or closed-course competition use only. By purchasing, you acknowledge responsibility for compliance with all applicable emissions laws and regulations. MAD disclaims liability for improper or unlawful use, and use on public roads may violate the Federal Clean Air Act and similar state laws.

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

BrandMAD MAD
Part NumberMAD-056
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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