i have a h/c/i c5 and there is a pump around here that sells 105 octane. is this safe to use in my car? i have heard it will destroy my o2 sensors.

 

Make sure it's unleaded fuel. The owners manual says low 90s octane for the original LSx motor. Lesser fuels are ok if that's all you can find...the PCM will adjust for it or reduce power. Engine load and altitude to a degree are considerations.

With you heads/cam motor, the 105 octane may or may not be necessary. Was the compression increased significantly? You might not appreciate any improvement in performance at a higher cost of fuel.

Can you check with the shop that built your motor?