Digital BW, The Print

I have been using and liking Red River's Fine Art White paper. However, when I print with it using the UT-14 ink set, including the Ebony black ink, position #21 in a step scale print never gets beyond 85. This is despite trying several borrowed ICCs and custom made ICCs using the Create ICC tool from QTR. Other than the fact that the ramps never get to 100, they are nicely even. Switching the Ebony black to regular black brings up the level very slightly, but never into the 90s. 

Is this just the nature of the paper or should I be doing something to increase the DMAX?

As is, the paper prints nicely, but lacks the punch of deeper blacks.