No, the Pro-Chamber is not catted. I believe that they are releasing a catted version this year; don't know for sure. The box you are referring to is called the mid-chamber. The way it works is that exhaust gasses mix from the two pipes in the chamber and the swirl and are accellerated out the back-end. It increases the flow and horsepower.
If it was me, I would go with the exhaust first. People tend to enjoy the car more when it has a good exhaust system on it. While you will defintely feel gears, I think you will enjoy the car a lot more when you and others can hear it coming; plus you get 2-4 mpg with exhaust whereas with gears you lose mpg (because you can't help but press the pedal )
I see. I'm not all that interested in the HP though. I'm more interested in which will have the loudest and best sound. Thanks for the HP numbers though. Could be good for future reference!
Do the exhaust ...but make sure you can pass emissions in your county. I passed on the x/with hi flows.They fail where I live. I have the Borla cat back.It's not quiet.