1994 Silverado 4x4 Catalytic question.
 

So I just picked up a 94' 4x4 Silverado with a 350(5.7) and I have this rattle in the cat. Upon inspecting I see only 1 cat right at the Y-connector for the exhaust with a pre O2 sensor. I'm not showing any SES's but the rattle is annoying. Could I just do away with the cat and not get any codes since the sensor is before it? Is any back pressure needed for that sensor? I haven't owned a V8 in many moons as all my stuff is V6 and 4cycl so the cat thing on this puzzles me.