See THIS THREAD for discussion on rack. It turns out that the fit kit for the G37 fits the Q50 perfectly. Measurements are slightly different from the ones in the Thule manual for the G, but it is easy to eyeball where things belong.
I bought the 1551 fit kit, the 480r feet and the aerobars - attached my 15 year-old Thule box. Very little wind noise and no problems at 75-85mph.