Performance M 4.5” Gen 2 B58 De-Cat G42 M240ix, G20 M340i, G29 Z4 M40i & A90 Toyota Supra

Unlock the B58’s potential with a 4.5 inch turbo down pipe upgrade for BMW and GR Supra

Give your B58-powered machine the flow it deserves. This catless front pipe is engineered for the G42 M240i xDrive, G20 M340i, G29 Z4 M40i and A90 GR Supra and is a proven route to faster turbo spool, stronger mid-range punch and a deeper, more purposeful exhaust note. It is the ideal foundation for tuning, remaps and Stage 2 calibrations.

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Why enthusiasts choose this hardware

• Noticeably reduced backpressure for quicker turbo response and improved throttle feel
• Full 4.5 inch bore from the turbo outlet for maximum gas velocity and power potential
• Deeper, more aggressive soundtrack with pronounced turbo spool
• Direct bolt-on fit for both right-hand drive and left-hand drive cars with no cutting or welding
• Compatible with the factory rear section and popular aftermarket cat-back systems

Premium construction

• Hand crafted and TIG welded from T304L stainless steel for durability and corrosion resistance
• Cast turbo elbow and smooth-radius bends for an uninterrupted transition from turbine to mid-pipe
• Oversized flex section to reduce stress and vibration on the system
• T304L grade stainless flange for a secure, leak-free seal

Options and warranty

• Catless version carries a lifetime warranty
• Also available as a 200-cell high-flow sports cat variant - the catted option has a one-year warranty

Real-world results

We run this hardware on our own builds and customer cars and the feedback is consistently excellent. Faster spool, stronger pull and a soundtrack that matches the performance.

Installation

Professional fitting is recommended. Book your installation with MJ Modifications in Warwickshire - request a quote at info@mjmodifications.co.uk.

For motorsport and off-road use where applicable.