Active Autowerke (AA) BMW N55 GESI High-Flow Catted Downpipe – No CEL – F30 F32 F87 M2 M235i 335i 435i – 304 Stainless Bolt-On

Active Autowerke GESI Sports Cat Pipe for BMW N55 F‑Series

Give your turbocharged N55 the flow it deserves with Active Autowerke’s GESI-equipped sports catalytic front pipe. Expect quicker turbo response, stronger mid-range pull and a crisper throttle feel, all while keeping the dashboard free from warning lights. Precision-built from T304 stainless with a massive 4.5 inch GESI G-Sport Ultra High Output catalyst and a free-flowing 3.5 inch bore, this direct-fit upgrade delivers serious performance with OE-style refinement.

At MJ Modifications we have installed and run this system ourselves. Fitment is spot on, the TIG welds are outstanding and our customers consistently praise the driveability and CEL-free operation. If you want a high quality, emissions-friendly N55 upgrade that works, this is the one.

Highlights

• No check engine lights when fitted correctly
• GESI G-Sport UHO 4.5 inch catalyst mated to 3.5 inch pipework for exceptional flow
• OBD2 compliant and EPA registered in 49 states
• Noticeably faster spool and stronger torque through the rev range
• Rated for roughly 500 to 850 hp applications and thermal loads up to 1500°F
• Reaches operating efficiency within seconds of start-up
• Direct bolt-on to the factory locations with no cutting or welding required
• Fully TIG-welded T304 stainless steel construction, including the catalyst canister
• Ultra high flow 400 CPSI catalyst, modular design and precise fit
• Designed and manufactured in Miami, Florida by Active Autowerke

What makes it a must-have

Turbo engines hate backpressure. The stock primary catalyst and narrow pipework choke flow and slow response. Active Autowerke’s straight-through 3.5 inch design reduces restriction, helping the single-scroll N55 turbo light up sooner and pull harder. You get a richer, more purposeful sound, smoother acceleration and headroom for future software and hardware upgrades while retaining daily comfort.

Vehicle applications

For BMW models with the N55 engine:

• 1 Series
  • F20 F21 M135i and M135i xDrive
• 2 Series
  • F22 F23 M235i and M235i xDrive
  • F87 M2 with N55
• 3 Series
  • F30 F31 335i and 335i xDrive
• 4 Series
  • F32 F33 F36 435i and 435i xDrive

On-road gains

Experience cleaner, stronger acceleration, improved transient response and a deeper tone under load, with excellent emissions control from the GESI UHO converter and no nuisance fault codes. The high-flow design supports future tuning while remaining refined for everyday use.

Installation at MJ Modifications

Professional fitting recommended. We offer installation at MJ Modifications in Warwickshire and can supply everything needed for a seamless, factory-style fit. For a quotation or to book your slot, email info@mjmodifications.co.uk.

Part number

11-040

Compliance and warranty

EPA certified for OBD2 vehicles except in California. Not legal for vehicles registered in the state of California. GESI catalytic converter carries a 5 year or 50,000 mile warranty.

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