Digital BW, The Print

I don't know if someone can help me but this group rocks!

I printed one of my picture using Mr.Roark's preset for Red River Polar Matte (using QTRip). The result was pretty good but I think that the blacks could be more defined.

I looked at Mr.Roark's ink limit and saw that it was 35%. Following his pdf, I tried to move with a test involving the ink limit set-up. Printing at 100% left me with a target so full of ink that even the text was blurred!
I made a test with 25% ink limit and another one at 15% ink limit on my 1430 EB6 set-up. Used my scanner to see what could be the results; the 15% ink limit is more defined than the 25% one and I'm asking myself, if this is normal to go so low?

I'm using the ink separation target.

And for some reason, I see that on the cyan line, one block (55) is darker than the 60 one; is this normal? All the other inks are OK.

Should I go on and try to get the best definition (separation) with the other inks?

Thanks