If you want a good strong motor that will have some power, dont baby it.
But at the same time, dont rag on it. Never keep it at the same RPM.
Keep it fluctuated. Keep the boost @ stock level. 14 ish PSI. (IF you have a trubo car)
You are gunna want to do this for 1,000-1,500 miles.

Change the oil often. You should have changed the oil after an hour of running the motor, and then again @ 100 miles. It goes like this.

Oil Change:

1 hour after running.

100 miles of driving.

500 miles of driving.

1,500 miles of driving.

2,500 or 3,000 miles of driving. <- one you hit this point, just start doing regular oil changes. Every 2,500 to 3,000 miles depending on how much you rag on the motor.

Modern engines are to the point of not needing a "pre-historic" break-in. Synthetic or not treat it like a new car. Break in periods happen with a rebuild or the Evo you just pulled off the lot.

Here is some more insight:

http://www.stealth316.com/2-breakin.htm

http://www.dsmtuners.com/forums/showthread.php?t=82689

http://www.dsmtuners.com/forums/showthread.php?t=75638

http://www.dsmtuners.com/forums/showthread.php?t=56188



Enjoy the reading.