Howdy and welcome. "Roof bars", you mean a carrier, I presume. Only thing to make sure of is that, if you have a sunroof, it will still open without the carrier interfering.
Do any of the very knowledgeable members of this board know if a roofrack system can be installed? I am thinking of a slim aero ski box for the winter and a bicycle rack for the summer. Thx for your input in advance.