[NCD1966]

you dont need the back O2s but you need the front ones for sure. I had some O2 simulators on my 98 Trans am. Then I ended up having the car dyno tuned and my tuner deleted the rear ones. I sold the sims to a guy tuning his own car.

Last I heard they dont make O2 simulators anymore. but I really dont know that for sure.
When I ran the simulators never really had a problem with them making my car run bad. Sometimes it would throw a code so I just unplug and plug them back and the code would go away.