QTR-Quadtone RIP

Hi all together! I have made a nice linearisation with my densitometer and my Eye-One using 
our own 7-Step-B+W-Ink-Set called "Carboprint-Ink" for Epson 2200 (in Germany: Epson 
2100) and the QTR for MAC Tiger. The only problem: I cannot get the highest possible d-max 
(thats around 1.76) on Hahnemühles Photo Rag. The max I get with QTR is 1.64 with 
boost_K:100 and grey_overlap: 10. I measure the 100% point at the 21-random-stepwedge. 
My questions: 1. what can I do more to get a higher d-max? 2. for printing the 21-random-
stepwedge is it neccessary to convert the stepwedge in the new QTR-gray workingspace and 
print with color-management incl. the QTR grey matt printer profile or do I have to print 
withour any color-management at this step? Thanks a lot for your help!!