Trample (ex) and Improved / greater overrun?

[Stikye]

Do those feats have any effect on the trample DC, or the add on effects?

Would an elephant with improved/greater overruns trample DC be higher because he adds bonuses to it? I don't think it would.

Does Improved overrun mean that trample no longer provokes AoOs?
Also, doubt it, but double checking.

Secondary, That same elephant, now tramples through a crowd with greater over run, does every one of his trample knock downs provoke due to greater over run? I think this one might.

Relevant abilities and feats.

Trample(ex):

As a full-round action, a creature with the trample ability can attempt to overrun any creature that is at least one size category Smaller than itself. This works just like the overrun combat maneuver, but the trampling creature does not need to make a check, it merely has to move over opponents in its path. Targets of a trample take an amount of damage equal to the trampling creature’s slam damage + 1-1/2 times its Str modifier. Targets of a trample can make an attack of opportunity, but at a –4 penalty. If targets forgo an attack of opportunity, they can attempt to avoid the trampling creature and receive a Reflex save to take half damage. The save DC against a creature’s trample attack is 10 + 1/2 the creature’s HD + the creature’s Str modifier (the exact DC is given in the creature’s descriptive text). A trampling creature can only deal trampling damage to each target once per round, no matter how many times its movement takes it over a target creature.

Bolded part that both says the feats might help, and might not.

Improved Overrun:

You do not provoke an attack of opportunity when performing an overrun combat maneuver. In addition, you receive a +2 bonus on checks made to overrrun a foe. You also receive a +2 bonus to your Combat Maneuver Defense whenever an opponent tries to overrun you. Targets of your overrun attempt may not chose to avoid you.

Greater Overrun:

You receive a +2 bonus on checks made to overrun a foe. This bonus stacks with the bonus granted by Improved Overrun. Whenever you overrun opponents, they provoke attacks of opportunity if they are knocked prone by your overrun.

[Amrel]

Nope, trample may work just like overrun, but it isn't overrun so RAW it doesn't work.

Doesn't seem like a bad house rule candidate though.