Toyota Supra Mk5, M240i G42, M340i G20, M440i G22 Large-bore Downpipe & Decat by Milltek Sport (2019+)
Fitment: Toyota Supra Mk5 (A90/A91) | BMW M240i (G42) | BMW M340i (G20) | BMW M440i (G22) — 2019 onwards, B58 engine
Unlock the full potential of your B58-powered machine with the Milltek Sport Large-Bore Downpipe & Decat. Engineered to replace the restrictive factory downpipe and catalytic converter, this precision-manufactured upgrade liberates exhaust gas flow from the turbocharger, delivering meaningful gains in power, throttle response, and acoustic character.
Hand-crafted from premium aerospace-grade T304 stainless steel, the downpipe features mandrel-bent, large-bore tubing to eliminate flow restrictions at the source — the critical bottleneck sitting directly beneath the turbo. The elimination of the primary catalyst allows exhaust gases to exit the turbine housing with minimal backpressure, which helps the turbocharger spool faster and maintain boost more efficiently across the rev range. Expect sharper throttle response, stronger mid-range pull, and a noticeable lift in peak output when paired with supporting modifications or a calibrated remap.
Sonically, the transformation is immediate. The deeper, more purposeful tone of the straight-six is brought to the forefront, with richer overrun crackles, sharper off-throttle pops, and a harder-edged bark under full load — all without descending into drone at cruising speeds. Whether fitted to the OEM cat-back or paired with a Milltek Sport cat-back system for the full Milltek experience, the character of the car is elevated to a level that the factory exhaust simply cannot match.
Every component is produced to Milltek's renowned standards, featuring CNC-machined flanges, TIG-welded joints, and perfect OEM-style fitment for a bolt-on installation with no cutting or fabrication required. All necessary gaskets and fixings are included, and the system is designed to mate seamlessly with either the factory exhaust or any Milltek Sport cat-back system.
Key Features
- Constructed from T304 aerospace-grade stainless steel
- Large-bore, mandrel-bent tubing for maximum flow
- Decat design removes the restrictive primary catalytic converter
- Faster turbo spool and reduced exhaust backpressure
- Deeper, more aggressive exhaust note with enhanced overrun
- Direct bolt-on replacement for OEM downpipe
- Compatible with factory and Milltek Sport cat-back systems
- Precision TIG-welded construction with CNC-machined flanges
- Backed by Milltek Sport's lifetime manufacturer warranty
⚠️ OFF-ROAD USE ONLY
This product is intended for off-road, motorsport, and competition use only. It is not legal for use on public roads or highways in jurisdictions where emissions regulations apply. Removal of the catalytic converter will trigger emissions fault codes, cause the vehicle to fail statutory emissions testing (including MOT in the UK and state emissions inspections in the US), and may render the vehicle non-compliant with local road traffic and environmental laws. It is the sole responsibility of the purchaser to ensure the product is used in accordance with all applicable regulations in their region. The manufacturer and retailer accept no liability for fines, penalties, or legal consequences arising from misuse.
Finance
Looking for a bit of flexibility when it comes to paying? We've got you covered. AUTOID has partnered with a number of payment providers to ensure a seamless buying experience.
Klarna
Select 'Klarna' at checkout to benefit from a number of finance options at checkout including:
- Pay Later - Delay payment by up to 30 days, interest free
- Split Payments - Split payments in 3 up to 3 months, interest free
- Installments - Split payments up to 6 months interest-free, up to 24 months interest bearing.
- 6 months - Interest-free Credit- Minimum: £250- Maximum: £5,000- 0% down payment/deposit
- 12 months - Interest-free Credit- Minimum: £250- Maximum: £5,000 Deposits are available and determined by the customer:
- 0% down payment for orders between £250 and £1000 (orders cannot be below £250)
- 10% - 50% down payment for orders between £1000.01 and £5000 - 24 months - Interest-bearing Credit - 18.9%- Minimum: £250- Maximum: £5,000
Deposits are available and determined by the customer:
- 0% down payment for orders between £250 and £1000 (orders cannot be below £250)
- 10% - 50% down payment for orders between £1,000.01 and £5,000
Klarna's Pay in 3 / Pay in 30 days are unregulated credit agreements. Borrowing more than you can afford or paying late may negatively impact your financial status and ability to obtain credit. 18+, UK residents only. Subject to status. Ts&Csand late fees apply.
Clearpay
Clearpay lends you a fixed amount of credit to allow you to pay for your purchase over 4 instalments (T&C's and eligibility criteria apply). They're ideal for purchases under £1000 and always offer interest-free*. For more details on how to use Clearpay to secure your order, get in touch with our team.
0% Interest. Select 'Clearpay' at checkout.
Please shop responsibly and visit lender websites for more information. All finance options are suitable for individuals 18+.
Milltek Sport

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Frequently asked questions
Yes! We offer installation services. Please contact our customer service team and we can provide a fitting quote for you.
All products sold on the AUTOID store are delivered with a minimum 6-month guarantee from ourselves.
Your item may also be further covered by a manufacturers that extends past the AUTOID guarantee.
Each product from their manufacturer will have it's own warranty period, please contact our customer service team if you sure unsure what that brand is covered by.
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WHY BUY FROM AUTOID
AUTOID is the leading destination for BMW M, Audi & VW aftermarket styling & Premium Carbon fibre upgrades. From front splitters and rear diffusers to intakes, exhausts and interior accessories, we deliver only the highest quality parts that transform your cars look and feel. Trusted by thousands of enthusiasts worldwide and rated 4.85/5. We back our products up with expert advice, fast worldwide shipping and a passion for innovation & vehicle styling.