BMW M135i Sports Cat / De-Cat Downpipe Performance Exhaust

Transform your BMW M135i F20 F21 with a high flow front pipe upgrade that unlocks power, sharpens response and unleashes a deeper, more purposeful soundtrack. This Cobra Sport turbo downpipe is engineered from premium 3 inch 76.2 mm T304 stainless steel and runs from the turbo outlet to the centre section, replacing the restrictive factory catalyst for serious flow improvements on the N55 3.0 turbocharged engine.

We have fitted these on customer cars and our own builds and the results are superb. Expect faster turbo spool, improved mid range punch and a more aggressive exhaust note without drone when paired with a quality cat back. Independent testing with the de cat configuration delivered gains of 20 bhp at the wheels and 28 lb ft of torque before any ECU calibration, making this the ideal foundation for Stage 1 and Stage 2 tuning.

Why choose this M135i downpipe upgrade

• Proven performance increase on the N55 platform with stronger low to mid range torque
• 3 inch 76.2 mm mandrel bent pipework for reduced back pressure and quicker spool
• T304 stainless construction for durability and corrosion resistance
• Direct bolt on replacement for the OE catalyst from turbo to mid pipe
• Enhanced sound with a deeper, sportier tone while allowing turbo whistle to shine
• Supplied with appropriate fixings and gaskets for a straightforward installation

Two configurations to suit your build

• High flow sport catalyst for freer breathing and strong performance while retaining a catalytic converter. Replaces the factory emissions unit and is not EC homologated. This may not meet current emission laws for road use in your territory.
• Catless front pipe de cat for maximum flow and the most aggressive soundtrack. Sold for motorsport and off road use only worldwide.

Fitment and compatibility

Designed for BMW M135i hatchback F20 3 door and F21 5 door with the 3.0 litre N55 turbo engine. Fits the turbo outlet to centre section path and pairs perfectly with stock or aftermarket cat back systems.

Ideal search terms customers use for this item

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Buy with confidence

Cobra Sport exhaust hardware is fully guaranteed for quality and finish. Our customers consistently rate this upgrade as one of the biggest bang for buck modifications on the M135i platform.

Professional fitting available

Want it installed properly first time with alignment and leak checks. Book fitting with MJ Modifications in Warwickshire. Request a quote at info@mjmodifications.co.uk.

Note: Performance figures quoted were recorded with the de cat configuration prior to ECU remapping and may vary by vehicle and setup.