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HFE BMW B58 Gen 1 4.5″ Decat Downpipe – M140i M240i M340i M440i Performance Upgrade
HFE BMW B58 Gen 1 4.5″ Decat Downpipe – M140i M240i M340i M440i Performance Upgrade
HFE BMW B58 Gen 1 4.5″ Decat Downpipe – M140i M240i M340i M440i Performance Upgrade
HFE BMW B58 Gen 1 4.5″ Decat Downpipe – M140i M240i M340i M440i Performance Upgrade

HFE BMW B58 Gen 1 4.5″ Decat Downpipe – M140i M240i M340i M440i Performance Upgrade

€306,95

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High Flow Engineering B58 Gen 1 Downpipe 4.5″ Decat Upgrade

Unlock greater performance from your BMW B58 Gen 1 engine with the HFE 4.5″ Decat Downpipe. Designed for models such as the M140i, M240i, M340i and M440i, this oversized high-flow downpipe replaces the restrictive factory catalytic section, significantly reducing exhaust backpressure and allowing the turbocharger to operate more efficiently. Ideal for Stage 2 builds and performance-focused vehicles.

⚠ IMPORTANT – EMISSIONS & ROAD USE NOTICE

This product removes the factory catalytic converter and is intended for off-road or motorsport use only. It is not UK road legal and will likely cause a UK MOT emissions failure. ECU tuning is required after installation.

Key Features＋
  • Oversized 4.5″ Diameter: Significantly improves exhaust gas flow.
  • High-Flow Decat Design: Eliminates restrictive factory catalytic converter.
  • Stainless Steel Construction: Durable and heat-resistant.
  • Mandrel-Bent Tubing: Smooth internal surface for optimal flow.
  • Improved Turbo Response: Reduced backpressure improves spool.
  • Aggressive Exhaust Tone: Enhanced turbo sound and exhaust character.
Why Upgrade Your B58 Downpipe?＋
  • The factory catalytic converter is a major exhaust restriction.
  • Reduced backpressure allows the turbo to operate more efficiently.
  • Essential upgrade for Stage 2 ECU tuning.
  • Improves throttle response and overall engine efficiency.
  • Complements intake, intercooler and charge pipe upgrades.
Technical Specifications＋
  • Material: 304 Stainless Steel
  • Diameter: 4.5″ high-flow tubing
  • Configuration: Decat (no catalytic converter)
  • Construction: Mandrel bent & welded
  • Fitment: Direct replacement 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
✔ ECU tuning recommended
✔ Off-road or motorsport use only

Installation＋
  • Remove factory catalytic downpipe.
  • Install HFE decat downpipe using OEM mounting points.
  • Check alignment and secure all connections.
  • ECU remap required before driving.
  • Professional installation recommended.
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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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Although our products may display an “In Stock” status, this indicator does not always reflect real-time inventory. Stock levels can change quickly, and some items may require additional processing time.

If you are working to a deadline, scheduling a project, or need your order within a specific timeframe, please contact us before purchasing via WhatsApp or the Contact us page so we can confirm availability and provide accurate lead times.

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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.
  • Faulty or incorrect items may be returned within 30 days for refund, repair, or replacement.
  • Customers are responsible for providing accurate specifications; we are not liable for errors due to incorrect information.

3. Damaged, Faulty, or Incorrect Items

  • All products are inspected before dispatch.
  • If your order arrives damaged, faulty, or incorrect:
  • Contact us immediately with clear photos of the product and packaging.
  • We will cover return shipping costs and issue a refund, repair, or replacement.
  • If a parcel arrives visibly damaged, sign as “damaged” (if possible) and notify us straight away.

4. Non-Returnable Items

  • Digital downloads, codes, or software
  • Custom-made, made-to-order, or special-order goods
  • Personalised products
  • Pre-orders not yet fulfilled
  • Gift cards
  • Used, installed, or modified items
  • Hazardous materials, flammable liquids, or gases
  • Services such as painting, ceramic coatings, or extended warranties

5. Exchanges

  • To exchange an item, return it via the standard process and place a new order for the replacement.
  • Customers are responsible for return and new delivery costs.
  • If the exchange is due to a faulty or incorrect item, we will cover return shipping and send the replacement free of charge.

6. Installation at D&C Prestige

  • Cancellations or changes made less than 48 hours before your installation appointment will forfeit your fitting deposit.
  • If you cancel and request a product refund, a 15% restocking fee applies, along with the deposit fee (if applicable).

7. Shipping & International Deliveries

  • In-stock items typically dispatch within 1–2 business days; some items may take up to 72 hours or longer during busy periods.
  • Tracking information will be provided once the order is shipped.
  • International customers are responsible for customs duties, taxes, and import fees unless the item is faulty or incorrect.
  • Refunds for international returns are issued in GBP. Currency conversion fees, bank charges, and international transaction costs are the customer’s responsibility.
  • We are not liable for customs delays, clearance costs, or refusal of goods by customs authorities.

For full details, see our Shipping Policy.

8. Digital Products (Downloads, Codes, Software)

  • Digital content (e.g., Bootmod3, XHP) is typically delivered immediately or within 24 hours via email or account access.
  • By purchasing, you agree that delivery is deemed to have started once payment is made, and you waive your right to cancel under the 14-day cooling-off period allowed by UK law.
  • 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.
  2. Wait for return authorisation and instructions before sending your item.
  3. Once received and inspected, we’ll notify you of approval or rejection of your refund.

Proof of return: Customers must retain proof of postage for all returns. Tracked and insured services are strongly recommended.

Refund method: Refunds are issued only to the original payment method used for the purchase. We cannot refund to alternative cards, accounts, or payment services.

Refused or undeliverable parcels: If a delivery is refused, unclaimed, or undeliverable due to incorrect address details provided, the customer will be responsible for return shipping costs and any applicable restocking fees.

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HFE BMW B58 Gen 1 4.5″ Decat Downpipe – M140i M240i M340i M440i Performance Upgrade