Syncing ONLY main Contacts folder from Exchange to iPhone5

I have several Exchange Contact folders and when I sync (over the air) with my iPhone5, they all come over.  Once on the iPhone5, i can filter the groups so I can only see the main one.  HOWEVER, I am trying to only SYNC the main Contacts folder to avoid having the 1000s of other contacts because that gives me fits with my Bluetooth connection to the car...  I have read other posts that say to make all the other folders main folders and not sub folders (by checking the box under properties->Outlook Address File->Show as email address book which i did) and they still all show up.  So, my question is, how can I limit the SYNC between exchange and the iPhone5 to ONLY the main Contacts folder?

Thanks!!