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big vs small turbos.....

          On the issue of big vs small turbos, a relevant quote from
          an article in the Sept. '93 _European Car_ magazine on the
          Cosworth Escort GT AWD Pro Rally car;
          ".....Turbo lag is the lasting impression of the engine.
           For homologation reasons, Ford has fitted the biggest turbo
           they could get away with on a production road car. After
           the first 2500 (required for homologation, Ed.) cars are
           built, however, they will revert to a smaller turbo
           unit.....  The cars built from then on should have plenty
           of down-low flexibility....."

          Audi faced the very same issues with the Ur Quattro, fully
          intending to homologate the automobile for Pro Rally use
          back in the very early 1980s, only Audi never reverted to
          a more sensibly sized turbo for street use after
          homologation was completed, till the advent of the S4 and
          20 valve engines. 

          I guess the S4 was never intended for rally or homologation
          use so fitting the largest possible turbo wasn't an issue,
          they could fit a smaller K24 unit and optimise the setup for
          real-world over-the-road performance.