Lil'Wayne

Do you need the special wiring harness for a 2008 chevy cobalt?

Hello. I’m helping my sister install an aftermarket radio in her four door 2008 chevy cobalt LT and I’ve been doing some research and from what I’ve heard, in GM vehicles newer then 2005 or so you need a special wiring harness like the “Metra LC-GMRC-LAN-03 GM LAN Data Bus Interface with Chime Retention” Which costs about 50 bucks on ebay. Apparently you need that harness so you don’t lose the open door ding, blinker sound, and all the other noises that the car makes. I’ve also heard that without the special wiring harness a bunch of other things will go wrong with your car like the gauges will not function properly and all the warning lights on your dash by the gauges would quit functioning. Now to me, that sounds like a bunch of crap. They wouldn’t design it to where you need the stock radio or the wiring harness for your gauges to work… that would just be stupid. The $50 wiring harness plays the notification sounds threw a little speaker that is connected to it. First off, if i do buy that wiring harness, that little speaker will be sitting behind the radio and behind all the trim so will you be able to hear it at all? I was thinking I would just buy a $10 wiring harness that will fit her car that doesnt have the little speaker. That would mean that she wouldn’t be able to hear any notifications though. She would be ok with no notifications, as long as it doesnt mess up the gauges and lights like i listed aboe. Is there any way to get the notifications to play? I was thinking that you could just splice a couple wires and get the notifications to play threw the cars speakers. Can I just connect the notification wire to a wire in the wiring harness that comes with the aftermarket radio?
Thank you for all of your help!