You're going to get a million different opinions because this subject is so subjective. That being said, I had the SPT on my '11 hatch and had the exact same goals as you have. In my own opinion, the volume of the SPT was nice and on the subtle side, BUT, the exhaust drones fiercely with the windows up. The connection from the midpipe to the muffler also hangs extremely low and looks tacky. These two factors made me ditch it. I found the drone to be far too much and gave me headaches...and I simply don't get headaches.
I moved on to the TurboXS GT series CBE. It achieves very similar volume levels as the SPT WITHOUT the drone. It also hangs nice and tight, with a nice esthetic finish. Check this out for a plethora of information.