Warrior tanks don't put out tons of DPS. Just give up that dream. Unless you're going to tank in Fury with dual Blades of Culling or something like that...
If you really want to maximize your DPS, make sure your ability priority usage is perfect and try for http://www.wowhead.com/item=50654
Defense isn't going to give you any extra DPS. It gives you block % chance (very small) but no block rating, which is the DPS component of SS.
What shoulder enchants do you have? +sta/+res PvP? That lowers the minimum defense to 536 vs 83 and 532 (I think it's 532) against 82s (Heroic 5m).
The idea of Prot Warrior + Massive DPS just don't exist except maybe when everyone else in your group is pulling 10K plus.
And the damage increase from titanium plating is almost irrelevent.