Without the ASR, or now with the ASR/exhaust valves closed on mine (10,000 miles) the exhaust is still pretty whisper quiet, the ASR improves the exhaust sound whilst you are driving 'slowly' or 'moderately' but as the exhaust valves open when your over 4500rpm anyway there are no 'noise' gains when your flat out.
With ASR it's a nice and welcome difference, there are no overrun pops and bangs (Audi say not possible with OPF but VW Golf 8R has them) you do get a slight gear change 'pop' though which is very welcome
I suspect that without the ASR I would have parted company with the car by now