I wouldn't take the car to the redline at 600 miles, but you could run it, 3/4 throttle, to the hp peak at 6200 rpm, its only 400 rpms from redline and should help to make the engine flexible as some others have said. I would Not take the engine to the redline until the 1200 miles have passed and you have done all the varying of speed, no full throttle starts, etc. When you read the maintenance recs, all they say, essentially, is go easy on the car. If you go past 4000rpm, do it smoothly and never with full throttle. As the skimpy explanation in the manual says, do everything easy and smoothly; it is up to you how you get to 1200 miles, just don't strain the engine. For an example, I always back off the gas immediately if I go over 4000 rpm and wait a 100 miles or so before I do it again during breakin.

Don't give in your baser instincts and drive ANY full throttle and your engine will breakin fine. This a tough engine, but its not a race car.

Boomer
BR/FR/AT

 

all cars i have owned had 500 mile break in period:

1. 1995 Civic EX (vtec)
2. 1998 Pathfiner SE
3. 2000 SLK 230 Kompressor

any particular reason why the Z needs 1200?