I have never heard that particular setup, but I would imagine it won't be a whole lot louder, if at all, just a different tone due to the X-pipe. Removing the cats is what really wakes it up and increases volume.
__________________ 2012 GT Premium, Brembo Package, M6
VMP Gen II S/C & Tune, GT500 Axle-Backs/Spoiler/Strut Mounts
Steeda Sports/Shocks/Struts, J&M PHB, GT/CS Chin, MMD Fog Deletes
I did long tube headers and a non catted x pipe with my v6 mustang awhile ago. I just didn't like the noise inside the car cabin, it sounded like a barrier was removed and you could hear the raspy air right below my feet.