I have an 03 A4 with the bose symphony stereo. I was looking in the trunk today and it seems there is a sub mounted under the rear deck. It looks like a 6” or 8”, anyone know the real size? Or is this just a regular speaker?

 

It sure is a sub, 8" 'Bose Nd NeoDymium Iron Boron High-efficiency woofer'.
Its backed by a Bose 215 watt amp which is under the decklid grill.
If you tune your Mids and bass settings properly, you can actually get some strong crisp bass out of it.
If you turn the mids down towards the negative side, you're bass should sound stronger.

 

http://www.audiworld.com/model/a4/03/03a4sedan.pdfthats the original spec sheet for your car, page 8 has the stuff about the bose-symphony system

 

Thanks man! Spec sheet is cool. Yeah the speakers don’t sound too bad, I would like a little more bass but at least it sounds clean and balanced, I don’t want it boomy, just a bit stronger, so I am going to go play with the settings a bit and see what I can get out of it.

 

Good luck with that. Right now my settings are at +5 Bass, -5 Mids, fade toward rear (2) and the treble also at 2.it makes my CDs sound pretty decscent.The bass sounds strong but doesnt over power everything else, so its still nice and clear no matter what your listening to, rap or rock, whatever.

 

Where could I find a spec sheet like this for the 2004 A4?

 

http://www.audiworld.com/model/a4/04/04a4sedan.pdfhere you go.....thats for an 04 sedan.......
all other models are here too:

http://www.audiworld.com/model/