As idk said you should be doing what you would do during a boss fight with perfect conditions to find what your upper limit is.
Be aware though that deliberately cheesing a pass to make it higher (using things you wouldn't in a real fight) doesn't help.
@Turelus - EU PC Megaserver "Don't count on others for help. In the end each of us is in this alone. The survivors are those who know how to look out for themselves."