Prety sure Rexilla put a Gonzo hot dog or something in his to quieten his down a bit.
Other way may be a 2.5" muffler, my APS muffler ain't too loud and does not drone with the rest of the RMS zorst....

i have a gonzo in my magnaflow system as well and it works well i dont have any drone in the cabin at all. it is meant to also give u slightly better performance. well so they say. its like a spiral looking thing inside.

girlfriend? rofl, no need for them they consume as much money as your car does but yea as ppl mentioned dynamat the whole damn car