BMW B58 Gen 2 5-inch High-Flow Catted Downpipe / Sports Cat (200-Cell Catalytic Converter) - G42 M240i xDrive, G20 M340i, G29 Z4 M40i - Toyota GR Supra A90 3.0

Unleash your B58 with a premium 5-inch sports catalyst turbo outlet pipe engineered for B58 Gen 2 platforms. Perfect for BMW G42 M240i xDrive, G20 M340i, G29 Z4 M40i and the Toyota GR Supra A90 3.0, this high quality upgrade transforms throttle response, improves flow and delivers a richer, more assertive exhaust note.

Why enthusiasts choose this sports catalyst

• Reduced exhaust restriction for quicker turbo spool and stronger mid-range punch
• Noticeable power potential and enhanced drivability, especially on tuned B58 setups
• Deeper, performance-led sound while retaining a high flow metallic catalyst
• Direct fitment with OEM precision and excellent long-term durability

Engineering highlights

• Full 5-inch diameter construction for maximum gas velocity from the turbo outlet
• Cast bellmouth elbow for a smooth transition from the turbine to the mid-pipe
• Oversized flex section to manage movement and reduce stress on the system
• Hand-crafted TIG welds throughout using T304L stainless steel with T304L flanges
• Mandrel-style smooth radius bends to minimise turbulence and increase flow

Fitment and compatibility

• BMW G42 M240i xDrive 3.0 B58 Gen 2
• BMW G20 M340i 3.0 B58 Gen 2
• BMW G29 Z4 M40i 3.0 B58 Gen 2
• Toyota GR Supra A90 3.0 B58
• Right-hand drive and left-hand drive compatible
• Bolts up to the factory cat-back and mates cleanly with aftermarket exhaust systems

Catalyst and materials

• High flow 200-cell metallic substrate sports catalyst
• Premium 304 and 304L grade stainless steel throughout for heat resistance and longevity

Warranty

• Lifetime warranty on the stainless pipework
• One year warranty on the catted section

Proven by us
We have fitted and used this setup on B58 Gen 2 builds and customer cars. Feedback has been consistently positive for fit, finish, sound quality and performance gains.

Professional installation
Want it fitted correctly first time? Book your install with MJ Modifications in Warwickshire. Email info@mjmodifications.co.uk for a quote.

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