Wastegate Noise

[gregsj@mail.imm.com]

When Audi was racing in the late ‘80s, they put a by-pass valve on the turbo so 
it could spool back up more quickly. If you watch any races from that era (e.g., 
TRANS AM or IMSA) you can hear the turbo b-p valve let go when Hans, Hurley or 
Walter shift. I've heard the sound described a a "turbo fart." My ‘91200TQW 
makes a noise similar to the one described in the post. I get full boost, so 
I've always assumed its just the b-p valve.