Invulnerable Rager Barbarian Theorycraft help

[Deadkitten]

So as far as I have gotten with it is that an Invulnerable Rager Barbarian with the Dragon Totem Rage Powers,and the rage power that increases Dr by one taken 3 times, and the feats combat expertise,endurance,diehard,stalwart, and improved stalwart can get DR29\- by level 20.

This amount honestly irks me.
Is there any way to increase this further, preferably to a nice,even number to alleviate my OCD?

Thanks in advance for anyone who feels like posting.

[Arksangiel]

Adamantine Armor should stack with that...

1/-, 2/-, or 3/-, take your pick.

[Arksangiel]

Thought the armor did but I can't find the text to back it up. Will read before posting next time.

[Iterman]

It doesn't stack, which is also why (I'm guessing) no one else has offered any advice (sad to say not even a prestige into stalwart defender would work).
The only way to increase your DR more is to have buffs that work in a manner similar to DR (Ablative Barrier will give you an additional quasi-DR/5 that also works with all other types of damage, [Greater] Infernal Healing will "add" 4 or 1 respectively to your DR for the first hit in the round). A four level dip into alchemist can be a very good dip if you want to go this route (you'll need at least a 12 int though).

[Cap. Darling]

If a round number is important i would Pick a level in unbreakable figther and another in Martial artist monk and only Pick increases DR Once that will leave you with DR 25 and Lots of feats to spare. Depending on nyour GM you could also kick the monk and get a level in the vermin focused hunter Archtype kill your PET spider and live your barbarian life with fast healing 1.