Shortened oil pans are the state of the art for Subie conversions, and
Subie powered sandrails.  They are not an issue. They are used by the
thousands.
   Shortened is a subjective term.  Because of its engine configuration,
Subaru puts a incredibly deep oil pan on their engines.  7 inches deep.
They do it because they can.  Deep is good.  Their engines are shallow
vertically so why not?
   Most commercially available shortened Subie pans are 4 inches deep.
Racing sandrails use the same thing, putting out 300-1000 hp and going
straight up and down without oil pressure issues.  If they needed a dry
sump, the racers would be using them.
   4 inches is deeper than most modern, stock, 4 cylinder engines.  A
great comparison - take a ruler to the pan on your WBXer.  Take away the
cooling fins, and it is 1 3/8 inches deep. 4 inches is still very
conservative.

   John
   Vanaru.com