you don't want one any way unless you're making 1k+ rwhp. At least that's what multiple tuners have said in the past. Something about losing torque and not gaining any power over a 2.5 mandrel setup.
I have only heard a prochamber once and I loved the sound it made with the MAC catback. It was deep and muscle car like. No raspiness at WOT eaither. I just really liked it. I figure my exhaust is fine but if I were to upgrade then it makes sense to get a 3" system