Best Sub amp for 1 12

I have one 12" Image Dynamics DVC v2 in a sealed box under the rear seat of my Tundra. Currently I am running an Xtant D class Mono sub amp, the 600.1, the new ones are called the 6.1 I believe.  I'm running at 2ohms so I should be getting around 600 watts.  I am not really getting any love from this sub, it sounds nice but there is not a lot of volume.  I have never used ID before, but from my friends who do use them, I am told they crave a ton of power.... soooo  question 1)  Should the amp I currently have work decent with this sub?  and if not 2) what amp might work great in this instance.  I have been looking at the Zapco 6.0, and I'm willing to spend about $1k for my new amp.  Suggestions please  =)

~Jay

I'm going to recheck the size of it tomorrow, the spec sheet that I found on my clipboard from when I origionally made this box shows different volume specs that what is posted on their webpage now.  I had origionally thought that the problem was that the volume was too large, but I had gone over my spec sheet a few times and came up nuts on.  I'll post back if I have the same problem after I spend the hours to get to where I can remove the speaker  =)