Exhaust questions

Hey all,

My exhaust is pretty much rusted through. Rattles like hell and getting annoying. The question I have is this. The truck has two sets of cats with one set looking like its part of the exhaust pipe itself.

Instead of trying to replace all the rusted clamps and heat shields I was thinking of putting a new system on. Would I run into any problem with a dual pipe setup? I viewed a guy that did a dual pipe in and out of a magnaflow muffler and twin pipe out to the rear. I don't really care much about sound per se, I just figure since its all shot to hell now would be a good time to do something.

Are there any mechanical issues I would come across such as removing O2 sensors or backpressure issues? Thanks in advance for any responses I get.