Our Pro-Flo 4 XT EFI Kit #35880 for rectangular-port Big-Block Chevrolet engines is a complete bolt-on electronic fuel injection system featuring a satin-finished XT intake manifold with large plenum and long tapered runners that comes ready to run with high-flow injectors; fuel rails and 90mm throttle body preassembled for you at the Edelbrock factory. We ve rated this kit at a maximum 825 horsepower with 60 lb/hr injectors and it includes all supporting sensors; a wide-band O2 sensor; wire harnesses and Android-based tablet. Also included is a single-connection distributor designed to work specifically with Pro-Flo 4 providing fully sequential port injection and infinite control over ignition and fuel events under all conditions. Key Pro-Flo 4 advancements are its Self-Calibrating Fuel Map Technology; Wide-Band O2 Closed Loop Mixture Control; and new low-profile ECU with faster processor and upgraded Bluetooth chip for reliable connectivity with the E-Tuner app that comes preinstalled on the tablet. Our E-Tuner app includes an easy-to-use Setup Wizard to guide you through setup and provides fuel and spark adjustability for complete control over the system. Pro-Flo 4 EFI #35880 for the Big-Block Chevy requires no laptop tuning. Minimal setup and tuning adjustments are required with base calibrations provided in the software. The ECU is self-learning and will continually adjust the fuel injection calibration for maximum performance by maintaining a specified target air-fuel ratio as you drive. The E-Tuner provides the ability to fine-tune air-fuel ratios; ignition curve; idle speed; acceleration fuel; fans; rev-limiter and more. Multiple displays let you monitor engine performance in real-time from inside or outside of the vehicle while retaining the simplicity that all of our Pro-Flo 4 systems are known for.