How much damage have you done (alone)? Is 1000 is possible?
Above is the most I've ever taken a screenshot of. The character was a Necro/Scribe/Mage, using a Dragon Slayer Scrapper's and I wouldn't say more than around 50 SDI otherwise, so nowhere near max. Of course it depends on the resists of the target, and whether you can Corpse or Omen, the target pretty much has to be weakest to fire or energy for the biggest spell hit. I don't know/think you can Omen Hailstorm (cold) (as a combo Hail/Omen I mean, obviously you can Omen/Hail but that would be at the risk of the target taking other damage), maybe after the changes, because I think it's instant anyway, not delayed like Meteor/Chain/FS.
So I'd say yes over 1000 should be possible. Though I don't recall ever seeing it, even when trying out things like Ogre Scrapper's Arctic Ogre Lord, Corpse FS/Omen, but then I've never used a suit that had max SDI at the cost of more important properties.