a friend of mine has a mach with flows and a bassani x, and it sounds wicked. it's more on the raspy side, and also has a real hollow sound that I enjoy.
I have the 40's on mine. I was running a bassani x (catted), and it sound pretty sweet, very deep and screamed WOT, but I wanted it louder so I swapped it for a mac o/r H and it sounds much better now. Cant go wrong with an o/r H.