I'm pretty sure you can install a subwoofer to just about any deck. Don't think you'll need an aftermarket deck. I would call a local car audio place and ask them, considering they probably see this all the time. I would still get an aftermarket deck though. I don't know about the interior of the Sierras, but me and my dad both have 03-06 body style Silverados and have both had problems with the stock stereos. His CD changer messed up and mine wouldn't eject the CD and a while after that just stopped playing music altogether. And you know with an aftermarket deck you can modify the tone of your music so that you have control of the bass, treble, etc.

If you wanted a double-din stereo you could get a Pioneer or a Kenwood and spend $200-300 for something that's really good for the money. You could also get a single-din and spend half that if you didn't care about all the extra bells and whistles. I have a Kenwood DDX418 and I love it; double-din, touchscreen, tons of features.

They have released the DDX419, which is the successor to the DDX418, since I got mine. Don't know what they added to the new one but it looks pretty much the same.

http://www.sonicelectronix.com/item_443 ... DX419.html

 

You need a line converter, Pac audio makes a plug and play that has the ability to use a 4 channel amp and it has a remote turn on, all you need to to do is plug it in run your cables, done deal! no cutting no splicing(except on remote lead)

http://pac-audio.com/productDetails.asp ... egoryID=28

 

Thanks guys...and yeah mine is starting to not insert the cd just waiting for it to completely die before i drop some big money on a new player. thanks for your help!