[Ed Wright]

Scott, if your only racing it you can have your "tuner" simply put it in open loop so the O2 sensors won't be used. If you are logging data with a wide band, I would change that sensor each season due to the lead. Lead skews their calibration, but not right away. In closed loop the GM PCMs would see the degraded factory sensors as a lean condition and eventually add fuel at WOT also to try to protect the engine. If it's an automatic car I see no real reason to run leaded fuel anyway.