Milltek Ford Focus MK4 ST 2.3 EcoBoost Large Bore De-Cat Downpipe | SSXFD337
Milltek Ford Focus MK4 ST Large Bore Downpipe & De-Cat – SSXFD337
Unlock the performance potential of your Ford Focus MK4 ST 2.3 EcoBoost with the Milltek Sport 80mm Large Bore Downpipe and De-Cat, designed for GPF/OPF-equipped models from 2019 onwards.
Engineered for motorsport and track applications, this high-performance exhaust upgrade replaces the restrictive factory catalytic converter with a free-flowing design, helping to reduce exhaust back pressure, improve gas flow and support increased power when combined with appropriate ECU tuning.
Manufactured in the UK using premium stainless steel, Milltek Sport exhaust components offer exceptional build quality, durability and precise fitment.
Key Features & Benefits
80mm (3.15") large bore diameter – Increased exhaust gas flow compared with the factory system.
De-Cat Design – Removes the catalytic converter restriction for motorsport performance applications.
Performance Potential – Supports improved turbo response and power delivery when paired with suitable Stage 2 ECU software.
Enhanced Exhaust Sound – Delivers a more aggressive exhaust character.
Premium Stainless Steel – High-quality construction for long-lasting durability.
UK Manufactured – Designed and developed by Milltek Sport.
GPF/OPF Compatibility – Designed for fitment with the original GPF/OPF or a compatible Milltek GPF/OPF bypass system.
Vehicle Compatibility
Ford Focus MK4 ST 2.3 EcoBoost Hatchback (2019 onwards)
Ford Focus MK4 ST 2.3 EcoBoost Estate (2019 onwards)
GPF/OPF-equipped petrol models only
Product Specifications
Manufacturer: Milltek Sport
Part Number: SSXFD337
Product Type: Large Bore Downpipe & De-Cat
Pipe Diameter: 80mm / 3.15"
Material: Performance stainless steel
EC Approved: No
Application: Motorsport / Track Use Only
ECU Software: Stage 2 Remap Required
Important Information
This product is intended strictly for off-road motorsport and track use. It is not approved for use on UK public roads. Removing the factory catalytic converter makes the vehicle non-compliant with UK road emissions requirements and will result in MOT failure where the missing emissions equipment is identified.
A compatible Stage 2 ECU calibration is required.
Why Choose OC Motorsport?
At OC Motorsport in Battlesbridge, Essex, we specialise in Ford ST and RS performance upgrades, including exhaust systems, performance tuning, servicing and track preparation.
Looking to upgrade your Focus MK4 ST? Contact our team for product compatibility advice and information about suitable motorsport performance upgrades.
OC Motorsport – Ford Performance & Tuning Specialists in Essex.


