Racing Lab B58 4.5-Inch Heat-Shielded Catless Downpipe

Developed for compatible B58 applications, this 4.5-inch catless downpipe replaces the restrictive factory primary catalytic converter with a straight-through exhaust path. The larger internal diameter reduces post-turbine backpressure, supporting quicker turbo response, increased performance headroom, and a louder, more aggressive B58 exhaust note.

The downpipe is manufactured from 304 stainless steel and enclosed by a thermal insulation layer that helps reduce radiant heat transfer to nearby engine-bay components. Factory-style oxygen-sensor ports support installation on compatible vehicles.

Common B58 Applications

• Toyota GR Supra A90/A91 3.0 B58 - 2019+
• BMW M240i / M240i xDrive - F22, F23 and G42 B58 models
• BMW 340i / M340i and xDrive - F30, F31, F34, G20 and G21 B58 models
• BMW 440i / M440i and xDrive - F32, F33, F36, G22, G23 and G26 B58 models
• BMW 540i / 540i xDrive - G30 and G31 B58 models
• BMW 740i / 740i xDrive - G11 and G12 B58 models
• BMW X3 M40i / X4 M40i - G01 and G02 B58 models
• BMW Z4 M40i - G29 B58 models

Features

• 4.5-inch straight-through catless design
• Integrated thermal insulation layer helps reduce radiant heat
• 304 stainless-steel construction
• Factory-style oxygen-sensor ports
• Reduced exhaust restriction and post-turbine backpressure
• More pronounced turbo and exhaust sound
  

Important Notes

• FOR CLOSED-COURSE COMPETITION / TRACK USE ONLY.
• This product removes the primary catalytic converter and is not intended for public-road use where emissions equipment removal is prohibited.
• A catalyst-efficiency warning light is likely without compatible ECU calibration; suitable tuning is recommended.
• Fitment can vary by B58 generation, production year, emissions specification, and GPF/OPF configuration.
• Confirm the VIN, turbo outlet, mounting bracket, and original downpipe configuration before ordering.
• Professional installation is recommended.