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MAD

5-Inch Catless B58 Downpipe

Name: 5-Inch Catless B58 Downpipe
Brand: MAD
SKU: MAD-052

$359.00 $309.43 Save $49.57

SKU: MAD-052

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Moderate — 2–4 hours

Overview

The MAD 5 inch Catless B58 Downpipe is a high-performance aftermarket upgrade for BMW B58 engine vehicles. It is constructed from premium stainless steel for durability and features a catless design to increase power and torque by improving exhaust flow. The downpipe has a 5-inch diameter, reducing backpressure for enhanced horsepower and torque output.

Show original supplier description

The MAD 5 inch Catless B58 Downpipe is a high-performance aftermarket upgrade designed for BMW B58 engine vehicles to increase power and torque while improving exhaust flow. This catless design eliminates the factory catalytic converter, offering further performance gains and an improved exhaust note, making it ideal for enthusiasts seeking to enhance their vehicle's performance and sound. Installation is straightforward with basic hand tools. Key features include smooth bends for maximum airflow without drone, compatibility with both right-hand and left-hand drive vehicles, and a flex section. This downpipe is compatible with a range of BMW models including the M240i, 340i, 440i, 540i, 740i, X3 M40i, X4 M40i, X5, X6, X7, Z4 M40i, and the Toyota Supra 3.0L (2019+). Notably, it does not fit 2025+ BMW M340i models.

Vehicle Symptoms

Check engine light with P0420 code
Reduced engine power and throttle response
Restricted exhaust flow causing poor turbo spool
Excessive backpressure and sluggish acceleration
Failed catalytic converter causing emissions test failure

Diagnostic Codes

P0420 - Cat Sys Efficiency Below Threshold (B1)

Relevant Conversations

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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.

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Specifications

Brand	MAD
Part Number	MAD-052
Category	Exhaust

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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

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