To Blow Off Valve or not to Blow Off Valve??

[aimre]

Here, ill add to mre confusion.

http://www.youtube.com/watch?v=OtMmze0KM6Q

At about 20 sec in, youll hear the Audi drive past, and u can hear it dose. But then at 50 sec, when the lancia drives past, it sound like its got a BOV.

Although audi won both constructors and drivers championship

BTW, there a bad accident in that, which marked an end to Group B rallying.... its safe to watch the first 1.20 min