Why would you want it to be quieter? Loud pipes saves lives! =p
Honestly, here in Singapore, drivers don't check their blind spots, don't signal before they change lanes, and can hardly keep in lane. That's why we prefer to have louder exhausts so that they can hear us, even if they can't see us. Riding a slightly noisier/louder bike has definitely helped me in avoiding accidents.
Note: This is coming from experience riding sewing machines like the Honda CB400.