Does anyone have a suggestion on how to make the bass drum unison sound more ";punchy";?  The unison sound just isn't as articulate as I would like.  Ideas?

I'm using Sibelius 6 (with template) and VDL 2.5.

Mark it with fff? I too have found that the bass drums sound ";nice";. But bass drums don't really sound ";nice";. Especially, the lower basses should sound much louder and boomier than the small ones, but they don't in VDL. There is a control on the Kontakt player which lets you add a bit more bottom end to the basses but there isn't nearly enough boost. I think that it is mostly the nature of percussion vs computer though. There is not nearly enough range available for volume and bass in computer playback. A standard accent on a real snare at least doubles the volume of the hit, but once you are into the range of forte on a computer, you can't double that volume, let alone a rimshot accent when the volume is at fff or even ffff. We wont talk about rfl and evfl settings.

I find writing out all five basses can get more punch than the actual unison note.  I'll write them into Layer 2 (not sure what Sibelius calls this), hide the layer, then put the note I want to display (bass unison) in Layer 1 and mute the note.

Otherwise using accents and heavier dynamics as Warren suggested may work as well.  Even if you don't want your bass drums to ever read a FFF note, you can add it and hide it for playback effect only.