I am in need of a new flex-pipe and (3) new cats plus all 02 sensors. Can someone explain to me exactly what the above picture means? I'm struggling to search for an oe-replacement flex-pipe and the right pre-cats/rear main cat that will give me the same performance,(if not better) for my 2003 Maxima SE 3.5L w/o gutting the cats. I live in Connecticut where emissions are very strict. The stock pipe is completely shot as well as all 3 cats.