QTR-Quadtone RIP

I recently completed a 5 gray ink set for an Epson 2200 with two cool 
toners. The carbon works great giving a very smooth warm print. The 
problem arises when I try to add cool toner. I get a significant drop 
in maximum black (over .07 in optical density). I tried using the toner-
curve.raw used by 2200 UT and I tried making my own toner.acv curves. 

I assume the objective is to keep the light toner inks out of the deep 
tones. I did that with my curve and also tried various combinations of 
toner shadow, highlight and gamma numbers, but no luck.  By the way, 
how can I see/modify raw curves? Photoshop doesn't open them.