Last I heard when a box makes less than what it is, that is called under achieving?
I think it made around 200hp right? That is no slouch but hardly an overachievment.
My biggest problem with the VA is the way they do timing, because the trannies don't work right with them. There have been a lot of us trying to figure out exactly what is does to the Allison, but there is something there.
If you can buy them cheap enough they are ok and can make good power. Make sure you can get replacement harnesses!