The Fabspeed BMW B58N Sport Catalytic Converter Downpipe is engineered to maximize performance, exhaust flow, and sound while maintaining catalyst efficiency and long-term reliability. Designed specifically for BMW vehicles equipped with the latest-generation B58N turbocharged engine, this premium downpipe replaces the restrictive factory catalytic converter with an advanced German-made HJS 200-cell EURO 6 homologated tri-metallic catalytic converter.

The factory catalytic converter utilizes a restrictive 12-inch-long 700-cell ceramic core catalyst that limits exhaust flow, suppresses exhaust sound, and restricts engine performance. Fabspeed developed this Sport Catalytic Converter Downpipe to eliminate those restrictions while maintaining emissions filtration efficiency and catalyst functionality.

The system features a large 4-inch inlet section from the turbocharger to the catalytic converter and a 3-inch outlet section from the catalyst to the remainder of the exhaust system. This design maximizes exhaust gas flow, improves turbocharger efficiency, enhances throttle response, and delivers noticeable performance gains throughout the RPM range.

Unlike many aftermarket catalytic converter solutions, the Fabspeed Sport Cat Downpipe utilizes one of the largest high-flow catalytic converters available that fits within the factory mounting location. The increased catalyst volume and expanded catalyst surface area allow for superior exhaust gas processing while supporting significantly higher horsepower levels.

Constructed from CNC mandrel-bent T304L stainless steel and assembled using premium German and American components, every downpipe is built for exceptional durability, corrosion resistance, and long-term performance.

This direct bolt-on replacement installs in the factory location without cutting, welding, or permanent modifications and is engineered to prevent catalyst-generated check engine lights on properly functioning vehicles.

Why Choose HJS German High-Flow Catalytic Converters?

Fabspeed utilizes genuine HJS Emission Technology catalytic converters manufactured in Germany and recognized globally for their exceptional performance, durability, and emissions efficiency.

HJS EURO 6 homologated tri-metallic catalytic converters are designed to provide outstanding exhaust flow while maintaining effective emissions filtration. Their advanced catalyst technology allows substantial increases in horsepower and torque while preserving catalyst efficiency and long-term reliability.

Advantages of HJS catalyst technology include:

• German-engineered EURO 6 homologated emissions technology
• Genuine HJS EMITEC tri-metallic catalyst construction
• Supports applications exceeding 1,200 horsepower
• Increased catalyst surface area for improved exhaust gas filtration
• Improved exhaust flow compared to factory ceramic catalysts
• Enhanced exhaust sound characteristics
• Long-term durability under street, highway, and performance driving conditions
• Flows up to 90-93% of a straight-pipe configuration in many applications
• Designed to minimize catalyst-related fault codes and warning lights
• Proven performance in street, Autobahn, and motorsport applications

Fabspeed Motorsport has served as the exclusive importer and distributor of HJS catalytic converter technology throughout North and South America for over two decades, ensuring customers receive genuine HJS components sourced directly from Germany.

Features and Benefits

• Fits all BMW B58N-equipped applications listed below
• Direct replacement for OEM catalytic converter part number 18325A04CB2
• German-made HJS 200-cell EURO 6 homologated tri-metallic catalytic converter
• Largest catalytic converter designed to fit within the factory mounting location
• Supports applications producing 1,200+ horsepower
• Significant performance gains throughout the RPM range
• Improved turbocharger efficiency and throttle response
• Increased exhaust flow compared to factory catalytic converters
• Enhanced exhaust sound and engine character
• Optimized to prevent catalyst-generated check engine lights
• 4-inch inlet tubing from turbocharger to catalyst
• 3-inch outlet tubing from catalyst to exhaust system
• Constructed from CNC mandrel-bent T304L stainless steel
• Built using premium German and American components
• Hand-assembled in-house
• Simple bolt-on installation
• No cutting, welding, or fabrication required
• Additional performance gains available when combined with ECU tuning
• Backed by the Fabspeed Lifetime Warranty

Fitment

Vehicle Compatibility:

• BMW X5 sDrive40i (2023–2024)
• BMW X5 xDrive40i (2023–2024)
• BMW X5 xDrive50e (2023–2024)
• BMW X6 xDrive40i (2023–2024)
• BMW X7 xDrive40i (2023–2024)

Fitment Notes:

• Fits BMW vehicles equipped with the B58N turbocharged engine platform
• Direct bolt-on replacement for factory catalytic converter assembly
• OEM Reference Number: 18325A04CB2
• Compatible with factory and performance exhaust systems
• No cutting or welding required for installation
• Additional power gains may be achieved with ECU tuning

Specifications

• Product Type: Sport Catalytic Converter Downpipe
• Catalytic Converter Type: HJS EURO 6 Homologated Tri-Metallic Catalyst
• Catalyst Density: 200 CPSI (Cells Per Square Inch)
• Material: T304L Stainless Steel
• Construction: CNC Mandrel-Bent
• Inlet Diameter: 4 Inches
• Outlet Diameter: 3 Inches
• Horsepower Capacity: 1,200+ HP
• Installation Type: Direct Bolt-On
• OEM Replacement Reference: 18325A04CB2
• Warranty: Fabspeed Lifetime Warranty