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.