Dinan Carbon Fibre/Fiber Cold Air Intake Induction Kit Airbox for BMW B58 G42 (M)240i, G20 G21 (M)340i, G22 G23 (M)440i – High‑Flow Performance Intake System with Filter | 2/3/4 Series 40i

Carbon fibre airbox upgrade for G‑series 40i models

Give your G‑chassis 2 Series, 3 Series or 4 Series with the B58 straight‑six the intake system it deserves. This premium carbon fibre airbox from Dinan replaces the restrictive factory setup and resonator, unleashing stronger top‑end pull, quicker throttle response and a rich, addictive induction soundtrack. It also transforms the look under the bonnet with a true OEM+ carbon finish.

Proven gains and real driving feel

• Dyno‑proven improvements: up to 9 WHP and 8 lb‑ft of torque at 6500 RPM on a stock vehicle
• Flows 58 percent more air than the factory assembly for sharper response and improved breathing
• Semi‑open layout with resonator delete heightens induction noise, turbo spool and blow‑off valve sounds
• Patterned secondary inlets add volume without raising turbo inlet temperatures

Engineered for airflow and aesthetics

• Large‑volume air box approximately 60 percent bigger than stock to maximise airflow potential
• High‑flow filter with 40 percent more surface area, from 82 in² to 115 in²
• Redesigned lower box fully utilises available engine bay space
• Stunning carbon fibre construction for a clean, OEM+ motorsport look
• Quick, straightforward installation

What you will notice

Owners report a deeper intake tone, pronounced turbo whistle and blow‑off sounds, and noticeably crisper pedal response. It elevates the character of the B58 without sacrificing refinement, making every drive more engaging.

Compatibility

Designed for G‑series 40i models powered by the B58 engine, including:

• 2 Series G42 240i
• 3 Series G20 G21 340i
• 4 Series G22 G23 440i

Suitable for cars with or without factory bracing, xDrive or rear‑wheel drive.

Why upgrade your factory intake

The standard air box is restrictive and muted by a resonator. This performance intake system delivers a substantial airflow increase, a more engaging soundtrack and a premium visual upgrade in the engine bay. More air in means better response and stronger pull across the rev range.

Professional fitting available

Want it installed by specialists? MJ Modifications in Warwickshire offers a full fitting service. Request a quote at info@mjmodifications.co.uk.

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