Spool Performance FX-350 High-Pressure Fuel Pump Upgrade for Audi RS6 Avant (C8) with EA825 Engine

What is the FX-350?

The FX-350 is an upgraded mechanical high-pressure fuel pump designed to significantly boost the performance of your Audi RS6 Avant (C8). With a larger bore size than the stock pump, the FX-350 provides approximately 90% more fuel flow, making it ideal for performance tuning. The pump is fully E85 compatible and features a plug-and-play design that requires no cutting or splicing. The additional fuel flow supports higher ethanol concentrations and can accommodate larger turbo setups, making it perfect for enthusiasts looking to push their RS6 Avant further. The FX-350 is also capable of running at pressures up to 350 bar, increasing fuel injector output and reducing injection times for enhanced performance.

The Spool Performance FX-350 sets a new standard in fuel system engineering, offering superior pressure and atomization for drivers aiming to achieve maximum performance from their Audi RS6 Avant.

Why Upgrade?

The stock high-pressure fuel pump in your Audi RS6 Avant can become a bottleneck when tuning for higher power. The FX-350 delivers 90% more fuel flow, enabling you to safely increase horsepower, run larger turbos, and use higher ethanol blends. This upgrade is crucial for serious performance enthusiasts seeking to unlock the full potential of their RS6 Avant.

Enhanced Pressure

The FX-350 is engineered to deliver fuel at an impressive 35Mpa, a substantial improvement over the FX-200’s 25Mpa. By applying the physics principle Q=PxA (flow rate = pressure x nozzle area), the FX-350 increases fuel flow by 40%, ensuring your Audi RS6 Avant receives the necessary fuel for optimal combustion, even under extreme performance conditions.

What’s Included in the Kit?

• 2 x FX-350 upgraded high-pressure fuel pumps
• 1 x Ethanol Content Monitor kit (optional), with mobile app
• 1 x Bosch spec 10-micron high-flow Fuel Filter
• Upgraded fuel lines and installation hardware

Spool 10-micron filter unit

The Spool 10-micron filter ensures top-tier filtration for your Audi RS6, protecting the high-pressure pump and injectors from debris without causing pressure drops in the low-pressure fuel system.

Spool Ethanol Content Monitor

The Spool ECA kit provides real-time data on ethanol content and fuel temperature through a mobile app. With BLE 4.0 technology, it wirelessly connects to your smartphone while remaining compatible with other Bluetooth devices. The kit’s fuel lines are black nylon-coated, braided steel with a PTFE core, ensuring full E85 compatibility.

Are Tune Changes Required?

Yes, the FX-350 requires calibration adjustments to prevent damage. Calibration details are provided for your tuner, and we can recommend experienced tuners familiar with the FX-350 upgrade. Custom tuning is essential to fully optimize the FX-350 for your Audi RS6 Avant’s specific configuration and driving conditions.

Low-Pressure Fuel Pump Upgrade

To protect your high-pressure pump and injectors, ensuring proper low-pressure fueling is critical. Insufficient low-pressure fueling can damage the pump and void warranties. Make sure your fuel system upgrades include low-pressure pump improvements when necessary.

We recommend the torquebyte controller to increase your factory low pressure pump's output by 60% to make sure the hpfp is always receiving sufficient low side flow. Please visit

Torquebyte EA825 Low pressure Fuel System upgrade

Unlock the full potential of your Audi RS6 Avant with the Spool Performance FX-350 high-pressure fuel pump upgrade.