QTR-Quadtone RIP

I have noticed (and a friend also commented on this) that I often 
will get a higher Dmax in my original InkSeparation.tif print than I 
do in my final profiles.  For example, a given paper may show a Dmax 
at 80% ink in the MK only test strip of 1.68, but when I complete my 
profile, using that ink limit, I usually lose maybe 0.03 to 0.05 
Dmax.  So, my final profile may show a Dmax of 1.63 or 1.64, instead 
of 1.68.

I have tried using a lower ink limit, for example 60%, then used a 
black boost of 80% for the MK ink, and I have also tried using a flat 
80% TIL.  In both cases, my final profile loses a little of its Dmax.

I am guessing that the addition of some lk, lc, or lm inks is 
actually lightening the ink in the blacks, or perhaps contributing to 
slight over inking of the paper.  So, I tried lowering the black 
boost (or overall ink limit) to 70% or 75%, but I still see that loss 
in all my profiles (neutral, warm, sepia, cool, coolSe).  

I am assuming that the settings in the Gray Toner tab might help lay 
down less ink in the deepest shadows.  I hate to give up any Dmax on 
some of the standard cotton papers, and some of them are coming in 
with a Dmax near 1.6 to 1.63 or so on my 4000 (using MISPro inks).

Have others noticed this?  Is there an easy/good way around it?  

Thanks, Lou Dina