Same thing happens with the 4.7L, mine supplies a 2.5v base bias.
I'm wondering if changing the bias would be a problem though, I noticed that upon engine start the voltage from the O2 sensor starts at 0v then slowly works it's way up over about 5-10 seconds to 2.5v, where it stays until the sensor is warmed up. Adding to this might upset the ECU? Guess it's a try it and see scenario as always.