The problem is most X-Force mufflers dont really do any muffling, they just look pretty..
You might have to put in a offset muffler somwhere under your car to get rid of the drone or if not change the twin loop for a better quality muffler like a remus/genuine twin loop.
Just adding on a extra resonator will make the sound less raspier and slightly deeper but it will still drone like crazy on the freeway or at cruise speed...
