On my car I tried to use the .91 voltage suggestion and I was running way to rich. The car ran .82to.86 on the O2's when I first had my 3L up and running with the MAF and injection system stock, and yes it was running just fine on A/F, a little rich even at high rpm. The voltage was .84 when I measured it after the first dyno tune of the car and provided about the best power with no pinging. I don't know if the O2 sensors are consistent from one to another but I would slowly lean it out until no more power is developed, then richen it just a tiny bit for protection from pinging.
warmonger
Former owner of '99 CSVT - Silver #222/2760
356/334 wHP/TQ at 10psi on pump gas!
See My Mods
'05 Volvo S40 Turbo 5 AWD with 6spd, Passion Red
'06 Mazda5 Touring, 5spd,MTX, Black