Why do you want to go beyond the power curve of the H22? Anyway, the ECU limits you to 7400 rpm and the tach may indicate 8000. Can you hurt the motor constantly winding it up-eventually you will cause wear and if you miss a shift break it. Can you tell if you've pushed it too much-the first thing I would expect is a rough idle and maybe some clattering sort of noise.
Do yourself a favor and find the point to shift where you loose the fewest rpm and still are able to accelerate. THis should be below redline.