The current O2 sensors aren't quite cutting it. About once a week the engine light turns on from the O2 sensor not getting "soaked". I have taken it to the dealership and a couple tuning shops and they have all said the same thing. The only problem is that none of the tuning shops have any real experience with the RX-8 and can't recommend a sensor that would handle it.

Any suggestions?

I've got a full RE-Amemiya exhaust, including, ex. manifold, high flow cat, and Super Dolphin II muffler.