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HFE BMW B58 Gen 1 5″ Decat Downpipe – M140i, M240i, M340i & M440i Performance Upgrade
HFE BMW B58 Gen 1 5″ Decat Downpipe – M140i, M240i, M340i & M440i Performance Upgrade
HFE BMW B58 Gen 1 5″ Decat Downpipe – M140i, M240i, M340i & M440i Performance Upgrade
HFE BMW B58 Gen 1 5″ Decat Downpipe – M140i, M240i, M340i & M440i Performance Upgrade

HFE BMW B58 Gen 1 5″ Decat Downpipe – M140i, M240i, M340i & M440i Performance Upgrade

£400.00£309.99

You Save: £90.01 (23%)

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High Flow Engineering B58 Gen 1 Downpipe 5″ Decat Performance Upgrade

Unlock maximum exhaust flow on your B58 Gen 1-powered BMW with the HFE 5″ Decat Downpipe. Designed for top performance in M140i, M240i, M340i and M440i models, this oversized decat replaces the restrictive factory section to significantly reduce backpressure, improve turbo response, and support higher power outputs — especially when paired with ECU tuning and additional performance upgrades.

⚠ IMPORTANT – ROAD USE, EMISSIONS & MOT NOTICE

This downpipe removes the factory catalytic converter and is intended for off-road, motorsport or track use only. It is not UK emissions compliant and will likely result in a UK MOT emissions failure. ECU remapping is strongly recommended after installation.

Key Features＋
  • 5″ High-Flow Decat Design: Massive bore for maximum exhaust gas flow.
  • Decat Configuration: Removes restrictive factory catalytic converters.
  • TIG-Welded 304 Stainless Steel: Built for heat resistance and durability.
  • Mandrel-Bent Tubing: Smooth internal profile for optimum flow.
  • Improved Turbo Response: Reduced backpressure enhances spool and throttle feel.
  • Loud & Aggressive Exhaust Tone: Sportier character at mid-high RPMs.
Why Upgrade to a 5″ Decat Downpipe?＋
  • The factory catalytic section is a bottleneck on boosted B58 Gen 1 engines.
  • Massive 5″ bore supports high horsepower and big turbo upgrades.
  • Lower exhaust backpressure improves overall engine efficiency.
  • Essential foundation mod for Stage 2+ and track builds.
  • Complements intake, intercooler, and charge pipe upgrades.
Technical Specifications＋
  • Material: High-grade stainless steel
  • Diameter: 5″ high-flow tubing
  • Configuration: Decat (no catalytic converters)
  • Construction: Mandrel bent & TIG welded
  • Fitment: Direct replacement for factory downpipe
Vehicle Compatibility＋
  • BMW M140i (B58 Gen 1)
  • BMW M240i (B58 Gen 1)
  • BMW M340i (B58 Gen 1)
  • BMW M440i (B58 Gen 1)

✔ B58 Gen 1 engine only
✔ For motorsport/off-road use only
✔ ECU tuning recommended

Installation＋
  • Remove factory downpipe and catalytic section.
  • Install HFE 5″ decat downpipe using OEM mounting points.
  • Check all connections for fitment and clearance.
  • ECU tuning is strongly recommended before driving.
  • Professional installation advised.
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⚠️ DISCLAIMER Unless explicitly stated otherwise, all products sold by DC Prestige Online LTD are designated race-only and are solely for competition or off-road use limited to racing formally sanctioned by a recognized racing organization. Any other use, including recreational off-road use, may be in violation of local, state, and Federal laws. DC Prestige Online LTD does not implicitly or explicitly confirm the legality of using any products it sells on public roads; that is entirely the responsibility of the consumer. Read our full terms of service here.

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Last updated: 07/09/2025

We want you to be confident when shopping with us. This page explains your rights and our terms for deliveries, returns, refunds, exchanges, and digital products. It applies to UK and international customers.

1. Standard Returns (UK & International)

  • Notify us within 14 calendar days of receiving your order if you wish to return.
  • Once approved, you have a further 14 days to send the goods back.
  • Items must be unused, uninstalled, and in original packaging, with proof of purchase.
  • Refunds are processed to your original payment method within 14 days of receiving goods (or proof of postage).

Note: Standard delivery costs will be refunded; upgraded shipping (e.g., next-day) is non-refundable. You are responsible for return postage unless the item is faulty, damaged, or incorrect. Used, installed, or damaged goods beyond reasonable inspection may incur up to 50% deduction from the refund.

2. Special Order & Custom Goods

  • Special-order parts must be returned within 7 days (if non-faulty) and may incur up to a 50% restocking fee, depending on supplier terms.
  • Custom-made or made-to-order goods are non-returnable unless faulty or not as described.
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  • Customers are responsible for providing accurate specifications; we are not liable for errors due to incorrect information.

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  • Cancellations or changes made less than 48 hours before your installation appointment will forfeit your fitting deposit.
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  • Refunds for international returns are issued in GBP. Currency conversion fees, bank charges, and international transaction costs are the customer’s responsibility.
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For full details, see our Shipping Policy.

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  • Refunds are only provided if the product is faulty, inaccessible due to our error, or not as described.
  • You are responsible for ensuring compatibility with your vehicle, hardware, or software; refunds are not offered if supplied correctly but incompatible due to buyer error.
  • International customers agree to the same terms.

9. How to Start a Return

  1. Visit our Contact Page and provide your full name, order number, and reason for return.
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  3. Once received and inspected, we’ll notify you of approval or rejection of your refund.

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HFE BMW B58 Gen 1 5″ Decat Downpipe – M140i, M240i, M340i & M440i Performance Upgrade