Well I did it. Got the Double DIN installed in my R53. Other than locating some wires to tap into it wasn't as bad as I expected. I used this mount: Scosche GM1590DDB Double DIN Dash Kit for Select 1992-Up GM & Select 1992-2008 Honda/Isuzu/Suzuki. I have auto climate control and the Alpine unit I picked (ILX-W650) was super shallow so I didn't even have to trim or relocate any of the HVAC parts. I mounted a 1/2" wide flat aluminum bar behind the HVAC/Switch panel and hung it off the top screws for added support so it runs behind the brackets. That probably wasn't really needed since during my mock up it was pretty solid anyway but since I had the material I did it just the same. Even got the steering wheel controls working.

 

Looks great! I've been wanting to do the same but don't want to lose the steering wheel buttons. How'd you get them to work??

 

Axxess ASWC-1. I've seen some posts about it not working but Metra must have updated the firmware, I had no problem. Power it on, hit the up volume button until the LED stops flashing, wait for reboot and it just worked.