ok guys, i bought my g/f a 2005 balt, it came with the upgraded cdplayer, but it doesnt support mp3.....i know i can buy a used one pretty cheap...i was told that they arent plug and play, something about they read the vin codes or something.....simple question, how is the swap done?

 

You will need to install and connect the new radio in the car.
Then bring it to the dealer and tell them you upgraded the radio and it needs to be unlocked.

I did the same to my balt. Cost me 33$ to have the radio re-programmed for my VIN.

 

I got a Sony Xplod mp3 deck, and when I finished my install, I found that none of my gauges worked with the stereo on. With some research on the subject, the only way the instrument panel and DIC will function properly.Is if you install a GM/LAN stereo installation kit.I got the Scosche GM1593 from cardomain.com for $112. Metra also makes one, I think the item # is 99-3303.
I know, that's alot of $ just to plug your new h/u into your car.But after you drive around for a few days not knowing how fast you're driving, or how much gas you have.It's kinda worth it. Both kits run regularly at $200, so shop around, and get one for alot less.
Now, my system's slumpin', from blocks ya hear me comin'

 

you dont need that kit.....please search

 

I didnt buy that expensive kit either. I have an 05 also. I bought like a $10 harness from crutchfield and installed my Pioneer flip out. Everything in my car works like normal!

 

X3
Dont by anything expensive unless you have onstar and want to keep it.
If you are simply just going to get another stock head unit you would just have to go to the dealership like what was said above. If going aftermarket there is nothing special.