i haven't heard either of the systems, but i love the sound of the prochamber. thats one of the set ups i'm contemplating.
when i was listening to clips i didn't like the magnaflow catted x too much, but the bassani one i really really liked. i think i have weird taste in exhaust clips though hah.
The prochamber will give you that aggressive bass sound that H pipes are known for and then some. In your case if you're splicing it into the O/R pipe you have it's probably going to be VERY LOUD. The magnaflow catted X will be more mellow and exotic sounding and depending of the muffler setup you have you'll have no drone.