is the underneath of all lt1s the same or is there a difference in the floorpan for single vs dual cat setups if not why should i get a dual cat setup if i can use o2 sims 2 cancel that part of it

just curious being that the dual cat stuff seems to be more expensive

 

Floorpan is the same on all f-bods of the same year. You'd want the dual cat setup if its legal in your area to change the cat configuration, more HP at higher rpms. The single cat strangles the motor at above 5k rpms. In some places, it is illegal to change the number of cats, usually as a rule of thumb, most muffler shops won't make a dual cat setup if it did not come from the factory that way, even on my '79 it was difficult finding a place to do it....now if your buying an out of the box setup and putting it on yourself...I haven't ran across an emissions place that cared here in TX at least, NJ or NY, etc may look at it differently.