This is about two feats I intend to use for a Large character :
Devastating Charge (Combat)
Prerequisite: Str 13, Power Attack, base attack bonus +1.
Benefit: When you are not mounted and you use the charge action, a successful attack deals an additional 2d4 points of damage. If you are using a 2-handed weapon, or a 1-handed weapon in 2 hands, you instead deal an additional, 3d4 points of damage.
Exalted Bullrush (Combat)
Prerequisite: Str 13, Improved Bull Rush, Power Attack, BAB +1.
Benefit: You can charge into a foe and use your body to damage him, while simultaneously pushing him backwards. When you make a Bull Rush, you also make a normal melee attack roll. (This is considered a charge.) If your attack roll succeeds, you deal melee damage. The damage is 1d3 if you are unarmored, 1d4 if in light armor, 1d6 in medium armor, and 1d8 in heavy armor. You add 150% of your Strength bonus to this damage.
Devastating Charge gives bonus damage dice not treated as precision damage, Exalted Bullrush is a new attack used in combination with a bull rush. For both, it looks like it would make sense to deal higher damage with a Large character or less with a Small one, like many other feats giving similar benefits, Head Butt is a good example.
So, are these damage dice unchanged by character size or should at least one of these feats deal more damage for larger characters and less for smaller ones ?