Daft question: the Subarus in the rally of GB seemed to be "twittering" or chirping like birds. Where are they kept?

I think it might be the dump valve, as it appeared to be loudest when approaching a corner? Anyone know? And why does it chirp? Dump to atmosphere with Anti lag kit?

Or is it just a loose wheel bearing?

 

Chiark,

Its the wastegate chattering away - wish mine sounded like that

 

Cheers, Rich. I thought it would be wierd if it was the dump valve, as it didn't only seem to do it when slowing down.

It almost sounded like a squeak at times, so I'm glad the answer wasn't, "it's the spare wheel bouncing around", which was my other half's suggestion