Someone recently posted in another thread that if you replace/upgrade the stock suspension, the ridgeline setting may be thrown off. I have done away with the stock Hennessy suspension ropes, and I also have the same issue as you in that I need some serious sag in my ridgeline in order to get a comfortable lay in my HH Expedition. If my ridgeline is at a suggested tautness (where you can barely bend it 90 degrees with your fingers when laying in it) I get a significant ridge in the center of the hammock where my calves cross over.
I am considering just shortening my ridgeline, which will allow me to pull it tight when setting up as well as raising up the bugnet a little higher away from me.
I'm interested in other's input on this as well.