OK so I got my Phatbox and took the aluminium cover off to give it the smallest size it could be.
It doesn't fit in either of the top two sections of the glove box but might fit upside down in the lower section. It may be OK the right way up if I manufacture a replacement cover and use industrial velcro.
The only other option there is to make a Phatbox size hole in the back of the glovebox to take it, which seems a bit drastic and could cause problems at sell on - unless I get a spare glovebox inner to match!!!
There isn't sufficient clearance under the front seats either as I tried and the storage under the front of those seats but it is the wrong shape to put it in.
So it looks like carving the back of the glovebox out or a boot install are the only options.
I really don't want to surface mount it in the boot as I carry lots of guitars, amps and ancilaiiry stuff and it would be in the way or get knocked about.
Does anyone know if the side panels in the boot come out easily? If so, maybe I could hide it in there. If I had the old A3 still, it could go where the multi CD player lives as there were nice easy to remove panels.
Maybe I could get a different panel to fit a 2004 A3 with the same 'door' in it as the 2001 A3.
All assistance and advice appreciated. I need music and I am fed up carrying loads of CDs in the glovebox.