[Dean]

I'm with Larry, and the people he references.

You have to let things set, but then you have to make sure you are stretching all the parts, and making sure they seat over their entire range of motion.

I personally believe this is especially true of rings/cylinders. If during break in you only rev to 4K at light load, the pistons will never have reached either of the extremes the would reach at 7K under high load. While this may only be thousandths of an inch, it is enough to leave some sort of ridge/uneveness at those extremes that can cause leakage or even damage to the rings later when the engine is run at those extremes.