I tried an Invidia catback system earlier this year, but took it off after a few months, bit louder and boomier than I hoped. Was recommended the Remus backbox as it's actually a Subaru option for the BRZ, which means it bolts up to the OEM midpipe and retains the factory resonator. The result is that this sounds a bit deeper and more mature, but isn't too loud when you don't want it to be. It's also suppressed the rather annoying metallic rattle I would sometimes get at low revs, which I think was caused by my OEM backbox not coping with the extra flow from the Ace manifold.
Will see how it sounds after a few weeks of settling in, but so far, the initial impression is good
