I had a muffler shop. Install. True dual exhaust on my 1997. C 1500. 305. It was running very poorly on the way home. I purchased. A couple sensor. Bongs. The kind that clamp on. And put my two forward sensors back in.I had a muffler shop. Install. True dual exhaust on my 1997. C 1500. 305. It was running very poorly on the way home. I purchased. A couple sensor. Bongs. The kind that clamp on. And put my two forward sensors back in. still runs like **** the downpipe originally had. 4 sensors. Two before the catalytic converter. And two after. Was wondering If it would be necessary To hook up the two rear sensors. Any advice with this problem I have would be greatly appreciated.