Explosive Power


The Explosive Power feat benefit description says:

As a full round action you may make a single melle attack using your highest BAB and utilizing Power Attack at your highest bonus. If the melle attack is successful, it is treated as a critical.

What exactly does it mean to use highest Power attack bonus? From the PA description, it seems it is not limited as to how much can you substract from your attack bonos to add to damage.

How are you using this feat?
I had a mental lapse when I posted this, but I realize the obvious now. Thanks any way.