As I said before, I think if I put the 02 sensors where the downpipe meet the header before it goes into one, I think it would work.
its been done, and it runs like shit. expect a 20-30 hp loss.
the o2 runs in pulse, 1/4 and 2/3 send out exhaust pules at the same time that its o2 sensor 'turns on' and looks for metering.