Breaker Rush (Ex): At 1st level, a siegebreaker can attempt bull rush or overrun combat maneuvers without provoking attacks of opportunity. When he performs either combat maneuver, he deals an amount of bludgeoning damage equal to his Strength bonus (minimum 1). If he has Improved Bull Rush or Improved Overrun, the damage dealt by the appropriate maneuver increases by 2 and he adds any enhancement bonus from his armor or shield (though such enhancement bonuses do not stack, if both armor and shield are magic). This ability replaces the feat gained at 1st level.
The bolded part someone interpreted it as making the damage 2 damage for 1 strength modifier, and another reads it as just getting 2 additional damage on top of the normal 1 for 1 ratio.
How much additional damage is dealt with let's say someone with 18 strength who succeeds on a bull rush attempt when they get the improved version using this ability?
I agree with leonvios. The more interesting question on the matter from my perspective is the following.
Does the fact that you add your armor enhancement bonus to damge mean that you also overcome damage reduction if your enhancement bonus to armor is +3 or higher?
Damage Reduction may be overcome by special materials, magic weapons (any weapon with a +1 or higher enhancement bonus, not counting the enhancement from masterwork quality), certain types of weapons (such as slashing or bludgeoning), and weapons imbued with an alignment.
My hunch is that by a strict RAW interpretation the answer is no as the rules state weapon enhancement.
Further question would the damage caused by the Breaker Rush ability be considered a weapon Damage roll in the sense of power attack?