The VMP unit is designed to be always on, it's a high efficiency unit and does not require any additional power wires or pressure switches. We do include a 30 amp fuse to replace the stock 20 amp fuse in the underhood fuse box. We hook ours up all the time to prevent any pressure spikes that may occur when a booster is triggered in the middle of a pull by a pressure switch. In the case of 05-10 Mustangs and other Fords that utilize a returnless fuel system, the computer is already modulating fuel pump duty cycle and only giving the car the pressure and flow it needs. For tuning, we recommending you reduce the Fuel Pump Voltage Table (under Returnless fuel pump) by 1-2 volts all over and fine tune from there by datalogging.. VMP Performance 05-10 Ford Mustang Plug and Play Fuel Pump Voltage Booster. VMP Fuel Pump Voltage Booster 40AMP with PNP Harness for 05-10 GT.. Supercharger Boost Sensor. VMP Fueling Accessories. Fueling Accessories

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