i was always under the impression that an x-pipe isn't as effective with chambered mufflers.
x-pipe will sound more aggressive and racier, h-pipe will be more bassy, traditional muscle sound.
that said, i went with a magnaflow catted x-pipe and magnapack catback. reason being is that mustangs are great down low but up top they're not the greatest performers, so with the x-pipe i was hoping to add more power uptop. plus, a majority of mustang owners go with the h and flows. i want to do something different. the catted x-pipe isn't raspy at all, it's plenty smooth. it doesn't drone out on the highway or anything. it's much louder outside than it is in. i set off car alarms in parking garages, but it's not overbearing.