Only thing that should change the sound is size (2.5" or 3"), cat or no cat and rea or no res aside from the ebay downpipes which I hear are thin wall tubing and sound different from the name brand downpipes that use better metal.
Cat. (And how many cells in the cat/highflow) or without.
Resonator. (Again based on size and design of resonator) or without.
Pipe diameter. (2.5, 2.75, 3" etc) (most downpipes for us are 3")
Any bends in them can change the harmonics of the piping.
The material of the metal and thickness of the walls.