[cal30_sniper]

The problem with the H-pipe O2 sensor is that your readings are very far removed from what the engine is actually experiencing. There's a time delay for the exhaust to get there, especially considering that you're going to have mixing and stagnation inside the crossover. Heat within the crossover is also much less than the collectors, which could screw up the readings (both actual composition of the exhaust, and what the sensor actually reads).

I would not advise putting the sensor in the crossover. Not saying it won't work, but it's definitely not ideal. The factory sensor only reads one bank, because it is placed as close as possible to the cylinder exit that can still get an averaged bank reading. That is for reasons of both temperature and response time.