Digital BW, The Print

I have been using the UT2 inkset in the R200. I've come up with a 
transfer curve to give an impressive result, except in the 65%-80% 
range, where the cyan (or light cyan) is too strong, giving a blue hue 
in that range. The rest is spot on, and I am most pleased with the 
(almost) results. I've tried everything in the Epson driver to 
compensate, have tried RGB curves, ATF curves, am stuck...am almost 
ready to start mixing inks, but that's a can of worms I'm sure I don't 
want to open. What kind of curve adjustments to neutralize/warm up 
this range and avoid the 'blue' look in that range? Thanks..Mark