The ex box is instead of mid pipes = mid pipes have nothing to do with an ex box. Mid pipes are used between the cylinders and mufflers (other than an ex box).
The S2R ex box pipes will not fit the cylinder head on a S4R. You can cut the pipes and have them welded in a "S2R ex box/S4R pipes" configuration, but that will probably be expensive.
I suggest: keep looking for a S4R ex box
![waytogo](http://ducatimonsterforum.org/Smileys/classic/waytogo.gif)