The Spritfire is NOT a voltage stabilizer or capacitor bank. It's a DC-DC converter that takes 12-14 volts of input (that's meant for the spark plug primary coil) and converting it to 16-18 volts output. As a result, it provides 25%-30% higher spark voltage at the secondary coil, thus increasing the usual 20-22kV spark plug voltage to around 25-28kV. It's still not as kick-ass as an external high-energy coil, though. Those things ramp up the secondary voltage to 45kV or more! But for regular folks, it's good enough for better combustion and a slight improvement in throttle response. But it's not one of those horsepower or torque increasing gadgets.