Spool Performance Audi C8 RS6 Avant FX-350 Upgraded High Pressure Fuel Pump System - SP-EA825RS6-FX350

The Spool Performance FX-350 Upgraded High-Pressure Fuel Pump System is a complete, high-output fueling solution engineered specifically for the Audi RS6 Avant (C8) equipped with the EA825 engine. Designed for high-horsepower and high-ethanol applications, this system removes the factory high-pressure fuel pump limitation that commonly restricts tuned and modified RS6 platforms.

At the core of this system are two Spool Performance FX-350 mechanical high-pressure fuel pumps, each featuring a larger internal bore than the factory units. This design delivers approximately 90% more fuel flow than stock, allowing the engine to safely support higher power levels, increased boost pressure, larger turbochargers, and elevated ethanol blends up to full E85.

The FX-350 operates at fuel pressures of up to 350 bar, significantly increasing injector efficiency while reducing injection time. Higher pressure combined with increased flow improves fuel atomization and combustion stability, especially under demanding performance conditions. Compared to lower-output pump solutions, the FX-350’s increased operating pressure directly translates into greater usable fuel delivery where it matters most.

This system is fully plug-and-play, requiring no cutting, splicing, or irreversible vehicle modifications. All components are engineered for direct fitment and long-term reliability. The FX-350 pumps are fully E85 compatible and built to withstand the demands of aggressive performance tuning.

To ensure fuel system protection and consistency, the kit includes a Bosch-spec 10-micron high-flow fuel filter, designed to protect both the high-pressure fuel pumps and injectors without introducing pressure drop on the low-pressure side. Optional integration of the Spool Performance Ethanol Content Monitor allows real-time ethanol percentage and fuel temperature monitoring through a mobile application, ensuring accurate tuning and fuel quality awareness.

The Spool Performance FX-350 system is intended for serious enthusiasts and high-performance builds. Custom ECU calibration is required to safely operate this system. Proper low-pressure fuel supply is also critical to prevent damage and ensure long-term reliability of the high-pressure fuel pumps.

Fitment

Vehicle Compatibility:

• Audi RS6 Avant (C8)

Model Years:

• 2020–2024

Engine:

• EA825 4.0T Twin-Turbo V8

Drivetrain:

• Quattro AWD

Notes:

• Designed exclusively for Audi RS6 Avant C8 with EA825 engine
• Not compatible with other Audi or Volkswagen platforms
• Custom ECU tuning is required
• Adequate low-pressure fuel system support is mandatory

What’s Included

• 2 x Spool Performance FX-350 upgraded high-pressure fuel pumps
• 1 x Bosch-spec 10-micron high-flow fuel filter
• Upgraded fuel lines
• Required installation hardware
• Optional Spool Performance Ethanol Content Monitor kit with mobile app support

Why Upgrade the High-Pressure Fuel Pump

The factory high-pressure fuel pump on the Audi RS6 Avant becomes a limiting factor once power levels, boost pressure, or ethanol content are increased. The Spool Performance FX-350 eliminates this bottleneck by delivering substantially higher fuel volume and pressure, enabling safer and more consistent fueling under extreme load.

This upgrade is essential for:

• High-horsepower builds
• Larger turbocharger setups
• High ethanol or full E85 applications
• Reduced injector duty cycle at elevated power levels

Tuning and Fuel System Requirements

• ECU calibration changes are required before operation
• Improper tuning can result in engine or fuel system damage
• Low-pressure fuel supply must be sufficient to prevent cavitation or pump failure
• Failure to support the low-pressure side can void warranties and damage components

Note: 'New' merchandise may be returned for exchange or refund within 15 days from the date of shipment. 'New' merchandise must be unused and free from installation or mounting damage. Installation or modification of parts waives your right to returns, refunds, or exchanges.