I have the Bose system and I want to put in an aftermarket headunit. Does anyone know where I can get the adapter to install it? Thanks.

I think best buy's install department sells them for like $20.

PAC makes one of the better units out there. Had one for a while when using the Bose head only with everything else changed. Worked as it should with no noise at all.
http://www.pac-audio.com/

Buy it here. Affordable Terminal Supply.
http://www.affsave.net/pac.htm

Mine is for sale. Went to a new head unit so I no longer need it. It needs one of the wire harnesses replaced. The part is available from Affordable Terminal too.

Cheers!

That were i got mine...make sure that it's the ROEM-NIS2. This comes with all the necessary harnesses just not the ROEM unit which you all so need. This is probably something that you want to read.