The OEM Aero Crossbar kit is nice and fairly inexpensive. If I'm not mistaken, your '06 should have 4 small removable tabs on the roof. Once you remove these tabs you will find your B9 ready to install the rack. 4 bolts (IIRC) under each tab and you're done. $142, here:
https://www.subarugenuineparts.com/product_info.php?cPath=73_77&products_id=872
Hope this helps.
https://www.subarugenuineparts.com/product_info.php?cPath=73_77&products_id=872
Hope this helps.