I have BOSE in my A3 and its not all that, it sounds very average,....not crap by a long way but not as good as you would expect.....saying that its 10 years old after all.
I'm a bit of a hifi geek when it comes to my stuff at home so it was a bit of a let down when I got the A3. I would ***** a load of money on it and change things around but the cash isnt there for that...if it doesnt make it go, stop or handle better I'll leave it. I can listen to glorious sound in my lounge..the cars for driving
A lad at works just got an E46 M3 with the posh stereo upgrade in it....oooof that sounds nice (I prefer the sound of the engien though!)