Roof Bars And Box For My Mk 3 Focus Hatch :). Any Suggestions Experience

[Carbonking]

hi all not sure if I should post here or not so sorry if I shouldn't .i am after some advice on roof bars and boxes .my car is a 2012 focus 5 door hatch it has holes in the door cill insides with rubber bungs in so I presume I need ones with mounting holes .now as I will have roof box on I don't know if square bars will be ok or I need aero ones and also as not used a box before I don't know how much noise there will be or if shape is essential I have a fair drive to South of France so need reasonable streamlining as such .any advice or experience would be greatly received as I am clueless about this subject. Looks like I could get a box about 1.7 m long without massive overhangs ( what over hang should I have) and up to about 900mm wide .thanks in advance for any information