Just parked by Bose equipped car next to the other '04 A3 we have here,with the standard set-up. We both have the same concert II single CD head units. I used the same tracks in each car (Win-you've got the power and Talking Heads-Once in a lifetime) in each car. It's pretty much what I expected. At low to medium-high volumes (anything up to around 12) the standard set-up offers much much better bass response,but with poorer top-end and seperation and a generally 'muddier' sound. Anything over 12 ,the Bose wins hands down as the standard set-up is starting to distort.Obviously the Bose speakers just need driven harder to work. Ultimate winner though ? '02 Golf fitted with a Pioneer headunit,powering all the standard speakers,plus a small Kenwood amp and Kenwood 6 x 9 speakers in the back shelf (proper sound shelf bought from ICE dealer). That set up cost him around £500ish,but blows either A3 away at any volume.