What size speakers are in the doors? How much depth is there for new speakers without interfering with the Window? Also I have the Symphony H/U 6 disc in dash with Bose spakers. I want to replace the factory speakers with something better, but I want to keep the factory H/U. I know I have to add new amps for the new door speakers and do some rewiring, which isn't a problem. Thanks

 

According to www.nexxia.co.uk you can get 6.5's in there. That's assuming you have an 02 A4 . I haven't heard any feedback about those adapters, but they look easy to install.

As far as depth, I don't know deep they can be exactly, but someone posted some pics of Kicker 5.25 woofers with huge magnets they got to fit in their doors.

There have been several posts in the A4 forum recently about splicing RCA's from the factory head unit to go the amps.