Sorry for redundant title, but after doing all the acoustic testing myself I became a big fan of thermal R&D because of the acoustic engineering they do. Same stuff I did, with mics and a laptop in the car mapping out resonance, etc. to calculate helmholtz chamber volume, etc. I haven't seen any other fiesta ST exhausts engineered quite the same way, so I am a fan even though I don't have one. Enough of my rambling, here's the video detailing their processes.
[video=youtube;j3iA_UtUWt4]http://www.youtube.com/watch?v=j3iA_UtUWt4[/video]
[video=youtube;j3iA_UtUWt4]http://www.youtube.com/watch?v=j3iA_UtUWt4[/video]