Hi
Im setting up a restoration project and am wondering if i install a body kit with these side skirts do they just go overtop of the metal under and the door and the fender or can i remove it? check out the files

 

they go over the metal and cover the mouldings. those side skirts have s5 style mouldings so it would look funny on your s4 unless you changed the rest of them.

 

whats the difference in the mouldings? how bad will it look and how hard is it to change?

 

the mouldings look completely different. it will look retarded, especially if you are trying to make the car look nice. to switch to s5 mouldings you would need to replace all of them including the front and rear bumpers. you might be able to cut the mouldings off the top of those side skirts...dunno how that would look/fit though.