I just got my Blitzsafe adaptor today and radio removal keys today, I pulled the radio out and checked out the back of the HU. I understand exactly how the blitzsafe connector will hook up, but my only question is where to ground it? I have heard you can tap into the brown wire on the stock harness but I don’t want to cut into that. Is it ok to just connect it to a screw that is touching bare metal on the back of the head unit itself? I can get a pic of the screw if needed, but I am pretty sure I saw it mentioned in an install guide somewhere. Otherwise is there a screw back there that touches bare metal I can remove and ground it to? I hope the back of the head unit is fine to do, but I know the ground is important so I don't want to mess it up. Found the how to that grounds to the back of the HU with no reported issues

http://forums.audiworld.com/a4gen2/msgs/218162.phtml