New to site and to Subaru. Just took delivery of 2014 Outback 3.6R with special appearance group. Looks good and rides great EXCEPT 60-70 MPH. Whole car vibrates. Feel mostly in butt. Sounds like some kid is in the back with a 500 watt amp and giant sub-woofer blasting. Took it back to dealer who load force balanced the wheels. Then swapped my wheels and tires for another. All without change. Service manager acknowledges problem but doesn't know what to do. I told him to check with Subaru techs or services reps for answers or solutions. Any one got same problem or suggestions?