You can hear a weird grinding, or fast knocking. Car is running lower boost than normal. Been looked through by 3 Subaru Dealers now and they claimed there was nothing wrong. At first, it took me some time to hear the sound in the car, thought it was the differential. But approaching full boost I started noticing what my friend has been describing. Use headphones if it is hard to hear, any input would be useful. The only thing one Service Department claimed was the Cobb downpipe, which does not have a bracket from the pipe to the transmission like the OEM downpipe is causing the rattle when in reverse. Looking at the tight clearance they are right about that rattle, but still they claim there's nothing wrong. I'm not familiar with any transmission/driveline work on any Subaru's yet, though one thing I noticed was how movement the transmission and driveshaft had, just from grabbing the exhaust and shaking it, can anyone help clarify anything?