Digital BW, The Print

When I first got my epson 1280 printer I ran a B&W print through it
using the epson inks (onto epson watercolor paper) that came with it.
 The print looked great! 
The blacks are very rich and the image jumps off the page.  I ordered
the cfs from cis along with epson archival inks and the double black
ink.  I ran the same image through and it looks real flat and the
black is nowhere as rich as the original inks.
I know that there is a difference between pigment and dyes.  Is this
the problem?  If so what is the solution?  I want to sell these prints
but I can't if the blacks look this bad.
Also, if i switch back to the non-archival inks what is the longevity?
Or am I using the wrong paper?

Thanks
dave