if you are using it 1:2 or 1:3 you might increase it to 1:1
or even a higher concentration of developer ...
you might also look into split filtration printing if you aren't already doing that
it might also help you get the contrast you want ...
there is an article on les mclean's website
right ... here: http://www.lesmcleanphotography.com/...ull&article=21
good luck !