BMW M140i Downpipe (Decat/Catless & 200 Cell Sports Cat) – B58 F20/F21 1 Series Turbo Front Pipe/Down Pipe | High Flow Catalytic Converter | Stainless Performance Exhaust | Stage 2 Tuning Ready | Cobra Sport

Unlock the full potential of your BMW M140i with a premium turbo front section engineered for flow, response and a richer soundtrack. This Cobra Sport upgrade replaces the restrictive factory catalyst with your choice of a high flow catted option or a straight-through catless pipe, delivering sharper throttle response, faster spool and a more purposeful tone on your 1 Series hot hatch.

Perfect for F20 and F21 M140i models running the 3.0 B58 turbo engine, this front pipe is built from T304 stainless steel with smooth mandrel bends to maximise gas velocity and heat management. Whether you are building a fast road car or a dedicated track tool, this is the foundation for Stage 2 tuning and a serious performance transformation.

Your options

• High flow catted: 4.5 in 114.3 mm 200 cell sports catalyst tapering to 3 in 76.2 mm pipework for excellent flow with reduced emissions compared to stock
• Catless: 3.5 in 88.9 mm straight-through design for maximum gas flow and response, motorsport and off road use only worldwide

Why enthusiasts choose this front pipe

• Dyno-tested platform with proven gains when combined with complementary hardware and software
• Noticeably quicker turbo spool and stronger mid-range punch
• Deep, aggressive tone under load while retaining cruising comfort when paired intelligently
• T304 stainless construction with precision mandrel bends for durability and consistent flow
• Supplied with all relevant fittings and gaskets for a straightforward installation
• Ideal with Stage 1 and Stage 2 remaps, JB4 and similar tuning solutions

Real-world results

On the AET Motorsport development car, switching to a full Cobra Sport turbo-back system with a catless front section saw 349.2 whp and 389.9 lb ft, up from a baseline of 327 whp and 367 lb ft. With additional tuning hardware and software, Map 5 recorded 423 whp and 453 lb ft. Your figures will vary based on supporting mods and calibration, but the platform potential is clear.

Fitment

BMW M140i 1 Series F20 and F21 3.0 B58 turbo petrol. Replaces the factory catalyst section from the turbo outlet to the centre pipe.

Road use and compliance

• Catless version: sold for motorsport and off road use only worldwide
• Sports catalyst: replaces an original emissions device and is not EC homologated. May not meet current road-going emissions requirements in your region

Install with confidence

We have fitted and run these systems ourselves at MJ Modifications in Warwickshire and our customers love the sharper response and refined sound quality. Want it supplied and installed by specialists who know the M140i platform inside out? Email info@mjmodifications.co.uk for a fitting quote.

Pairing suggestions

For the best results, combine this front section with a quality cat-back system, performance intake and appropriate ECU calibration. This optimises backpressure, fuelling and boost control for stronger, repeatable gains.

Media

Sound and First Drive - BMW M140i Stage 2 - Cobra Sport Exhausts

Exhaust Talk Episode Two - Sports Catalyst vs De-Cat Performance Exhausts

Search-friendly terms

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