Active Autowerke GESI G-Sport UHO High-Flow Sports Cats (HFC) / Catted Downpipes for BMW M5 F90 & M8 F91/F92/F93 (S63TU F9X) - Primary Front Pipes, 304 Stainless, V-Band, Bolt-On, EPA/OBD2 49-State, No CEL/EML | PN 11-063

GESI high-output sports cats for BMW F9x V8 twin‑turbo models

Give your F9x platform the flow it deserves with this premium front catalyst assembly by Active Autowerke. Engineered for the S63TU motor in the saloon and grand tourer variants, this upgrade replaces the restrictive primary section with ultra high output G-Sport converters for serious gains in response, stronger mid-range punch and a cleaner, crisper exhaust note. Expect quicker turbo spool, reduced back pressure and rock-solid reliability from a system designed to look factory under the bonnet and fit like it was made by BMW.

Crafted from 304 stainless with beautiful TIG welds and mandrel bends, the layout uses an OE-match 3.5 inch V-band inlet and includes the lower section that many brands sell as a separate mid piece. You can retain your original oxygen sensor heat shields for a stealth appearance. It is a direct replacement that requires no cutting or fabrication.

Why enthusiasts choose this sports cat upgrade

• Transforms throttle response and turbo spool on the S63TU twin-turbo V8
• Optimised gas velocity for noticeable torque and horsepower improvements
• Designed to avoid engine management warnings when used as intended
• OE-style fitment with V-band connections and provision for factory heat shields
• Full front section supplied, not just a short pair of primary pipes
• Durable 304 stainless construction with TIG-welded precision
• Manufactured in the USA by a highly respected BMW performance specialist

Technical details

• Part number: 11-063
• Pair of 4.5 inch GESI G-Sport Ultra High Output catalytic converters
• 400 CPSI substrate with proprietary precious metal loading for high efficiency
• OBD2 compliant and EPA registered for 49-state use, not CARB approved
• Rated for applications from 500 to 850 hp
• Withstands exhaust gas temperatures up to 1500 °F
• Rapid light-off, reaching operating efficiency in approximately 9 seconds
• Factory-matched 3.5 inch V-band inlet with high-flow, mandrel-bent tubing
• Accepts OEM O2 sensor heat shields for a stock look
• Direct replacement installation with no cutting or welding required
• Precise fit for the F9x chassis
• Catalyst warranty: 5 years or 50,000 miles

Vehicle fitment

• F90 M5, including Competition and LCI
• F91 M8 Convertible
• F92 M8 Coupe
• F93 M8 Gran Coupe

What we have seen in the workshop

We run this setup on our own builds and have installed it for many customers. Feedback is consistently positive: faster spool, stronger mid-range pull and impeccable build quality. It is a proper solution if you want performance with a refined driving experience and a near-OE appearance.

Professional fitting

This assembly is a straightforward direct replacement. For installation, book our in-house fitting service at MJ Modifications in Warwickshire. Email info@mjmodifications.co.uk for a tailored quote and availability.

Compliance and use

GESI UHO converters are EPA registered and OBD2 compliant for 49-state use. They are not approved by CARB. Always check and follow local regulations. Federal law prohibits tampering with emissions control devices. Mobile Source Enforcement Memorandum 1A permits aftermarket parts for repair or replacement provided emissions performance is not adversely affected.

Search terms customers use for this item

BMW F90 M5 sports cats, M5 Competition front pipes, BMW M8 primary pipes, F92 M8 catalytic converter upgrade, F93 Gran Coupe performance cats, S63TU high flow catalysts, F9x V-band front section, stainless 304 exhaust upgrade, GESI G-Sport UHO 400 CPSI, EML friendly cat upgrade, turbo spool improvement for S63, UK BMW tuning parts, PN 11-063.