BMW B58 (F-Chassis) FATBOY 5" Downpipe

The HARPIA Performance Parts FATBOY 5 inch Downpipe for BMW B58 is designed to maximize exhaust flow and unlock the full potential of your B58 engine. This high-performance catless downpipe replaces the restrictive OEM downpipe with OPF, significantly reducing back pressure, improving turbo spool, increasing power and delivering a deeper, more aggressive exhaust sound. Manufactured from high quality stainless steel with precision TIG welds, it features a 5 inch (127 mm) diameter for maximum flow and durability.

Key Features:

• Catless design (no catalytic converter)
• 5 inch (127 mm) FATBOY diameter
• Significantly reduced back pressure
• Improved exhaust flow and faster turbo spool
• More power and enhanced exhaust sound
• High quality stainless steel construction
• Precision TIG welds
• Direct replacement of the OEM downpipe (with OPF)
• Rigorously tested for quality and durability

Vehicle Compatibility:

• BMW B58 with OPF filter: M140i, M240i, 340i, 440i, 540i — all variants with B58 engine and OPF

What's Included:

• 1 × FATBOY 5 inch Downpipe (Catless)

Warranty: 6-month HARPIA Performance Parts warranty. Covers manufacturing defects.

Note: this listing currently shares specs with our G-Chassis FATBOY downpipe pending F-chassis-specific confirmation — please contact us with your VIN to confirm exact fitment.

Brand

Harpia Performance

Downpipe

Downpipe

Orders ship within 1-2 business days. Returns accepted within 30 days on unused parts.