I was reading the combat maneuvers section and was reading the disarm part.
You can attempt to disarm your opponent in place of a melee attack. If you do not have the Improved Disarm feat, or a similar ability, attempting to disarm a foe provokes an attack of opportunity from the target of your maneuver. Attempting to disarm a foe while unarmed imposes a –4 penalty on the attack.
So for the unarmed -4 penalty, does that include if you have improved unarmed strike?