BMW B58 4.5 Inch Catless Downpipe - M240i M340i 440i 540i 840i / Toyota Supra A90 2016-2024 - OneFastShop

Take the restriction out of your B58 with the OneFastShop 4.5 inch catless downpipe. The factory catalytic converter is the largest restriction in the exhaust - removing it frees up real power, spools the turbo sooner, and opens up the deep, aggressive growl the B58 was built to make. Fits a wide range of F chassis and G chassis B58 BMWs plus the Toyota GR Supra A90 from 2016 to 2024.

Expect +30 to +40 horsepower with a supporting tune (more on upgraded turbos), faster spool, and sharper throttle response. It's a direct bolt-on with no cutting required, works with OEM and aftermarket cat-back exhausts, and is backed by a lifetime warranty on defects.

Specifications

What's in the Box

• 1x B58 4.5 inch catless downpipe
• Welded mounting bracket

Installation & Tuning Notes

Gasket required: A turbo-to-downpipe gasket is required to seal the downpipe to your factory turbo. Our 4.5 Inch Turbo to Downpipe Gasket for BMW B58 and Toyota Supra is sold separately - add one to your order.

Tuning & check engine light: Removing the cat means the rear O2 sensor will eventually set a check engine light (a catalyst efficiency code such as P0420) on an otherwise stock car. This is normal for any catless downpipe and not a fault with the part. To run it correctly and keep the light off, the car should be tuned with the rear O2 sensor turned off - any major B58 tuning platform supports this. We strongly recommend installing this downpipe with a supporting tune rather than on a stock vehicle.

Off-road use: Intended for off-road and track use only. Not legal for use on public roads and may not comply with emissions regulations. Check local laws before installation.

Fitment