Active Autowerke S58 High-Flow Sport Cats / Catted Downpipes for BMW X3 M & X4 M F97/F98 2019+ (Competition) | GESI G-Sport UHO Catalytic Converters | 49-State EPA OBD2 Compliant | 3" 304SS Front Pipes | Part 11-070

Active Autowerke S58 High-Flow Catalyst Upgrade for BMW X3 M and X4 M

Unlock sharper throttle response, quicker turbo spool and a richer, more purposeful soundtrack with this premium high-flow catalyst front section engineered specifically for the BMW S58 in the F97 X3 M and F98 X4 M. Built around GESI G-Sport Ultra High Output converters, it delivers emissions-friendly performance, OBD-II readiness and the durability enthusiasts demand from a daily driven performance SUV.

We have fitted this unit on customer cars at MJ Modifications and the feedback has been outstanding, with stronger mid-range punch, improved drivability and a deeper tone that stays refined on the motorway. It is a true bolt-on upgrade designed for enthusiasts who want power gains without constant warning lights or compromise.

Why this high-flow catalyst is a brilliant upgrade

• Reduces exhaust back pressure so the S58 turbos come on boost faster
• Noticeable gains in torque and responsiveness across the rev range
• Deep, assertive exhaust note under load, civil at cruise with no unwanted drone
• Engineered for reliability on mapped or stock vehicles
• Designed to minimise the chance of a Check Engine Light when installed correctly

Key specifications

• Part number: 11-070
• Pair of GESI G-Sport UHO high-flow catalysts, 4.5 inch diameter, 400 CPSI
• OBD-II compliant and EPA registered in 49 states, not CARB approved
• 3 inch primary tubing in 304 stainless steel, smooth transition to OEM 70 mm
• CNC cast stainless V-band for precise, leak-free sealing
• TIG-welded 304SS throughout with stainless flex joints for durability
• Accepts factory BMW lambda O2 sensors and the OEM O2 heat shield
• Rated for 500 to 850 bhp applications
• Withstands up to 1500°F and reaches operating efficiency within 9 seconds of start-up
• Direct bolt-on installation, no cutting or welding required
• Made in the USA, Miami Florida

Fitment

• BMW X3 M F97, 2019 onwards, including Competition
• BMW X4 M F98, 2019 onwards, including Competition

What you will feel

Faster spool, stronger mid-range torque and a cleaner, more engaging exhaust character. The S58 breathes more freely, which translates to punchier acceleration and a more responsive feel in every driving mode, from daily commuting to spirited B-road blasts.

Installation and support

Professional fitting recommended. MJ Modifications offers installation services in Warwickshire. Request a quote at info@mjmodifications.co.uk.

Emissions and compliance

• EPA registered and OBD-II compliant in 49 states
• Not legal for use on vehicles registered in California, not CARB approved
• Designed to reduce the likelihood of a CEL when installed correctly
• Observe all local regulations regarding emissions equipment

Warranty

5 year or 50,000 mile warranty on the catalytic converters.

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