well, im putting an s2000 engine in my '90 rx-7, and my engine came without any o2 sensors. Since im using the honda ecu, I need to have both o2 sensors running.

I dont want to get the factory o2 sensors since they are pretty expensive. I have heard of people using the universal bosch heated o2 for the primary sensor, but what about the secondary sensor? is there a cheaper bosch one for that too?

if you would like to read about and see pics of my swap, click hereSWAP