I have a 2000 s4 with a concert series radio system, how hard is it to replace it with the bose system and has anyone done this.

 

If you're going to replace the system, get something better than Bose. While Bose sounds nice and clean, you're very limited on how loud you can crank it. I put in a Pioneer AVIC-Z2 with Focal speakers, a couple of amps and a JBL sub. It was on the pricey side but well worth it. You can watch DVDs, it records your CDs onto a hard drive, navi, XM, etc, and the sound is amazing.

 

Go go aftermarket. I put in a Alpine CDA-9885 to match the red light and get HD Radio. You can find all of the wiring mounting required on ebay for pretty cheap. If you are having any issues let me know. Just so you know many places like best buy or car toys are going to say you have rewire the entire car when that is not completely true... at least it wasn't for me.