Active Autowerke B58 GESI Catted Downpipe – BMW G2X M340i / M440i

Unlock the true performance of your BMW G-Series B58 with the Active Autowerke Signature Catted Downpipe, engineered for maximum flow, faster turbo response, and reliable daily drivability. Designed specifically for the G2X platform, this upgrade removes the restrictions of the factory downpipe while maintaining efficiency with advanced GESI catalytic technology.

Featuring a 4.5” GESI G-Sport Ultra High Output catalytic converter, this downpipe delivers strong performance gains while minimising the risk of check engine lights - making it one of the most refined high-flow catted solutions available.

Now includes turbo flange gasket pre-installed to ensure a hassle-free installation.

Key Features

• Direct fit for BMW G2X B58 vehicles (M340i / M440i)
  
• 4.5” high-flow GESI G-Sport catalytic converter
  
• No CEL for catalytic efficiency
  
• Pre-installed turbo flange gasket
  
• 4.5” primary piping tapered to 3.5” and 80mm OEM connection
  
• Improved turbo spool and throttle response
  
• Increased horsepower and torque output
  
• Cast stainless steel V-band for precise fitment
  
• Bolt-on installation – no cutting or welding required
  
• TIG-welded 304 stainless steel construction
  
• Rated for 500–850 horsepower applications
  
• Withstands temperatures up to 1500°F

Performance Benefits

Engineered to maximise B58 efficiency and output.

• Faster turbo spool with reduced lag
  
• Improved exhaust flow for higher power potential
  
• Stronger mid-range and top-end performance
  
• Enhanced throttle response and drivability
  
• Ideal for Stage 1 and Stage 2 tuned setups

GESI Catalytic Technology

High-performance emissions control without compromise.

• 400 cell ultra high-flow catalytic converter
  
• EPA registered and OBD2 compliant (non-CARB regions)
  
• Designed to minimise or eliminate CEL
  
• Proprietary precious metal loading for reduced emissions
  
• Full 304 stainless steel substrate for durability

Build Quality

Built for high-performance and long-term reliability.

• Full 304 stainless steel construction
  
• Furnace-brazed catalytic core for strength
  
• Precision engineering for OEM-level fitment
  
• Designed to withstand extreme heat and boost levels

Installation

• Direct bolt-on replacement for factory downpipe
• No cutting or welding required

Professional installation recommended

Installation available at Sequential Racing – Altona North, Melbourne

Vehicle Fitment

• BMW G20 / G21 M340i
  
• BMW G22 / G23 M440i

Engine: B58 3.0L Turbocharged

Important Notes

• Not legal for use in California (CARB restrictions)
  
• Designed for performance use depending on local regulations
  
• Warranty may be void with excessive burble settings

Warranty

• 5 Year / 50,000 Mile warranty (shell and tube ends)
  
• 2 Year / 25,000 Mile warranty on catalytic core

Why Choose Sequential Racing?

Sequential Racing supplies premium performance upgrades for BMW and GR platforms, focusing on proven products that deliver real-world gains with OEM-level reliability.

• High-flow performance with minimal compromise
  
• Trusted Active Autowerke engineering
  
• Easy installation with strong performance results

Upgrade your BMW M340i or M440i with the Active Autowerke B58 GESI Catted Downpipe and experience faster spool, increased power, and refined performance.