I havent seen anyone here talk about these speaker adapters but I bought them and am very happy with mine. They fit perfectly and shipping was very fast. I replaced my 4.5 factory in the front with 5.25.

http://www.nexxia.co.uk/Speaker_adaptors/audi.htm

 

actually the reason people probably dont talk about it is because the bose speakers themselves are quite damn good for what they are. For little itty bitty stock 2ohm speakers they give a wallop. I changed my reardecks because they blew (someone installed them stupidly).... and I also got a kenwood 10 inch sub. Fun stuff. Im glad for ya though... lots of money and hard work.

 

The bose are pretty good for a stock stereo system.

But thats a good find Wemmington. The adapters once made by another company have stopped production.
I made my own though, when I put my Infinity components in the front - was a pita.