I don't have any dyno numbers but this was my experience on my '09 Standard with 3 pipe system.
TORS and Staintune cat delete were louder than stock but not excessively. You don't get a deep rumble though; some say a little raspy. I reckon they sounded a little like a Brit sports car - say, a Jaguar. Staintune or MadDog pipes, for example, will give a deeper sound.
Performance seemed better, especially low down. I think TORS, having a slightly smaller internal diameter than say, Staintune, are actually designed with torque increase in mind more than hp. My bike did spin out really well too and, with triple K&N filters and a Dobeck was as quick as anything else out there and certainly more than fast enough for me. As noted, you will need either a tune or some other way to increase fuelling. The stock Triumph TORS tune is too lean on its own. I used a Dobeck and still have the TORS tune and it works fine.
The TORS and filters have now gone and are sitting in my garage. New set-up is definitely better, so I'd view TORS as a more than adequate and very cost effective system for moderate gains and good sound. I was very happy with it and changed it opportunistically rather than due to any performance issue (although I did want better sound).