Milltek Sport HJS Tuning 300 Cell ECE Approved Sports Cat Downpipe BMW 4 Series M440i (F32/F33) Coupe & Gran Coupe, xDrive & RWD, 20172020 SSXBM1039_3

Milltek HJS 300 CPSI Sports Catalyst Downpipe for BMW 4 Series M440i F32 F33, xDrive and rear wheel drive, 2017 to 2020. Part number: SSXBM1039_3

Give your B58-powered M440i a serious breathing upgrade with Milltek’s HJS-equipped catted downpipe. Built in Britain from premium Type 304 stainless steel and finished to an exceptional standard, this high-flow sports catalyst transforms response and delivers a clean, purposeful soundtrack without unwanted cabin boom. It integrates perfectly with the factory system or a Milltek cat-back for a refined, performance-focused setup that you can enjoy every day.

Why this performance sports catalyst stands out

• HJS 300 CPSI EU type-approved sports catalyst for quality, reliability and compliance
• Free-flowing design to reduce backpressure and sharpen throttle response
• T304 stainless steel construction for corrosion resistance and long-term durability
• Mandrel-bent tubing to maintain consistent diameter and optimise gas velocity
• Engineered sound that is sporty and crisp without drone
• Designed, developed and hand finished in the UK
• Seamless fit with OEM exhaust or Milltek rear sections
• Tried and trusted by us and our customers. Feedback has been outstanding
• Easy reference for ordering: SSXBM1039_3

Vehicle compatibility

BMW 4 Series M440i F32 and F33, Coupe and Gran Coupe, xDrive and non xDrive, model years 2017 to 2020. Not sure if this suits your car? Get in touch and we will confirm fitment before you buy.

Build, tone and drivability

Milltek focuses on flow efficiency and sound development to deliver performance you can feel without compromising refinement. The HJS 300 cell catalyst and precision pipework allow the turbocharged straight-six to breathe more freely, while comprehensive acoustic tuning ensures a mature note with zero intrusive resonance.

Professional fitting

For installation, we recommend booking with MJ Modifications in Warwickshire. Request a fitting quote via info@mjmodifications.co.uk.

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