When you use the attack action, you can make one attack at your highest base attack bonus that deals additional damage. Roll the damage dice for the attack twice and add the results together, but do not multiply damage bonuses from Strength, weapon abilities (such as flaming), or precision-based damage (such as sneak attack).
The text of this feat stipulates that the vital striker does not multiply Strength damage, weapon ability damage, or precision damage. Are other damage bonuses (those not mentioned, such as those from Weapon Specialization, enhancement bonuses, or the bard's inspire courage ability) are, in fact, multiplied on a hit? I'm not sure if that's what is intended, though--the wording sounds like it could just be saying, "No damage bonuses, such as X, Y, and Z, are multiplied on a hit."
Considering it says to multiply the dice rather than multiply the damage, I'm under the belief that you ONLY roll more dice, then add the other bonuses in as normal.
yes, that's also my interpretation, but I have a player trying to rules lawyer and the wording is a bit confusing.