As mentioned in the GT. I had my car serviced and it was brought up that my secondary turbo actuator (ECV) has developed a rattle at idle. However I can't hear it at idle to be honest. When he tried to demonstrate I had to rev the motor (not a lot) then it will rattle off throttle. He wasn't sure how to adjust this, generally he works on single turbo Subaru's, but he is very good. He wants to ask around himself before giving it a go another time.
I searched the forum and found a guide to adjust, 'ADJUSTING ECV OPERATION ROD' http://www.subyclub....-to-twin-turbo/. If I'm brave enough I might try this if its necessary. The car does run fine, it has a stock tune (to my knowledge). I can definitely feel the boost down low (have a boost gauge) and changeover is usually pretty quick when I'm generous with the go pedal. It can delay a bit on occasion. Maybe it just needs a slight adjustment? If you have any other helpful input, let me know.