Fitting price was for the full turbo-back!
Sound: It is a very quiet system, unless you are on WOT (Wide Open Throttle). In terms of normal driving, you can hardly hear it inside the car, however once you hammer it, then it becomes louder. Even inside the car when hammering it, it is not intrusively loud. (all of the aforementioned comments are with the windows up)
However, if you open the windows, then you can hear the exhaust. And when you are flooring it, it is really quite loud, and people will definitely hear you coming!!! Holding 70mph on a motorway it is much quieter than the stock system.
It makes a lovely noise - it has a rasp to it similar to an E46 M3 / motorbike!!!