as for the O2 sensor, if i am right, your injection system is a "batch fire" type, rather than a sequential system, therefore it should be more suited to a single O2 sensor, to be on the safe side though, add a balance tube to the exhaust system and fit the sensor in the middle of it, that way, it can "see" both cylinder banks.
please don't take my word for it though, all these electrickery type things confuse the f@*k out of me.
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I KNOW WHERE YOU LIVE......
I'M JUST TOO DAMNED TIRED TO BOTHER CHASING YOU !