Does it sound like this?
[ame="http://www.youtube.com/watch?v=_3sycuN_keA"]FA20 (BRZ) boxer motor tapping - YouTube[/ame]
Sorry for wind noise...Everything else is normal. That was a GBS Limited at idle, iPhone vid taken right above the driver's side fender where it meets the hood.
I've read that Subies are known for that tapping, but I haven't come across any tapping from the turbocharged variants.