QTR-Quadtone RIP

I'm creating some cool and warm curves for Moab Kayenta and a 2200
with UT7 ink.  I'm happy with the dMax of 1.600 but dMin is running
0.130.  Ideally shouldn't it be 0.000?  How would I get it there?  If
I were to increase the value of the Gray Curve Highlight would it
bring the dMin down?  Right now I have the highlight at 4.

Thanks,

Tom