One of the guys she went to supposedly works on Subaru's all the time. Personally i told her to try the 02 sensor. She doesnt want to listen so i am about to wipe my hands clean with it.
She had a VW before her subaru and she didnt listen to me with that either. She had a constant buzzing with it when she hit 2k rpms, She took it all over, spent tons of money. People saying it was the oil pressure sensor, saying it was an electrical issue. Every time the buzzing went away for like a week or 2.
Finally she listened to me, Changed the oil using a thicker oil and an OEM filter and the buzzing went away for good. (VW's are picky with Oil filters, something with the back pressure) I know it sounds unbelievable about it being oil and a filter but it worked.