I found this awesome video of an Audi S1 Group B rally car.  I really do miss these things in the Rally Championships, they were obviously completely mental and dangerous but superb entertainment!  A few highlights to look out for is the compressor surge at 1m:03s, where air is trying to force the turbo to spin backwards or something and the sound is the air battering the turbo blades, bad for the car but great for the ears.  Also the donuts at 3m:09s!

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