Modifications or replacements of components within a vehicle's fuel delivery system to enhance performance, efficiency, or accommodate increased power demands. This can include upgrades to fuel pumps, injectors, fuel lines, fuel rails, and fuel filters. These modifications are often necessary when increasing engine power through modifications like turbocharging or supercharging, as they ensure a consistent and adequate fuel supply. Upgrades can also improve fuel atomization and delivery, resulting in better combustion and increased efficiency.