An all-wheel-drive Audi S2 running a Precision 6466 turbocharger on a 2.2-liter five-cylinder against a nitrous-fed Chevelle leaning on cubic inches is one of the oldest arguments in street racing, staged in metal. Turbo versus nitrous, import versus muscle, four driven wheels versus two. The horsepower numbers are only half the story. Read on to find out which factor usually decides it.