most people are happy when their aftermarket catback exhaust systems are quiet. you want to sound like an angry bumblebee?
if you really do want it to be louder, get your muffler's perforated louvre core ported and polished at a good muffler shop. sometimes they can have residue on them from when they were stamped out at the factory, and it disrupts airflow, creating a sort of "baffling" effect like your old stock muffler. if you can afford it (and if you can find a shop in your area with the right equipment), have the resonator extrude honed. that will force impurities out of the exhaust. this will be especially important if you get a header, since that will eliminate one of your cats.