Thats why we relocate the sensor on the 4 bangers about an inch away from the main exhaust flow with the sparkplug anti fouler. You still have the computer see the sensor, but it just gets "fooled" in simple terms. No codes, and no backfire.The presents of the O2 sensor causes the processor to look at the gas to air ratio in the exhaust pipe. In doing this the fuel ratio is forced to be controlled by the O2 sensor and not the new processor. You don't want this. Very little change takes place as long as the CO sensor is in use. The motor will or could improve some, but you will not get the real benefit of the processor as long as the O2 sensor is still in line.