I was thinking...since there are o2 sensors for measuring before the exhaust enters the catalytic converter and there are sensors that measure after it...would it be possible to "trick" the o2s? My idea is have 2 separate exhaust manifolds required of a true dual, plug the 2 pre-cat sensors 1 into each as per factory setup, have 2 catalytic converters 1 per manifold wherever we can find space for placement, then plug the remaining 2 sensors (obviously a Cali spec here) after the converters, then run the pipe from there to the rear of the car etc etc. From what I was told the post-cat sensors work by comparing the measurements that the pre-cat sensors send to the computer. Not really tricking the o2s I know but that's my idea.