We are in the process of re-formulating the PK ink with a new very-very-very dark pigment and dispersion technique. This is for ConeColor PK. We are seeing L values in the 2-4 range when not under printed with any other ink on gloss paper. The gloss is the same as OEM epson but it's slightly more translucent as well meaning the darkest shadow detail is actually better than OEM PK while maintaining full dMax.
It takes a while to go from R&D to full production and then QC, bottle-filling, and final sale (it's still in the first phase). We will send emails out to all when this stuff is ready for buying. We are INCREDIBLY excited about it because it means that we can possibly very well run it for Piezography PK ink as well to enable a whole slew of ideas we have up our sleeves.
The trick is to make this PK ink darker AND cross compatible with old curves and color ICC profiles. That is tricky because it comes down the finely controlled pigment amounts. (This is different than what epson does by coming out a with a new K ink and forcing everyone to buy a new printer).
That said, dye will always be darker. Trade-off is the archival nature between dye and pigment.
So yeah, working on it. Stay tuned.