I left this post in the impala forum, but I'm sure it applies to most chevys now.

I just got a 2003 impala, and I'd like to add a few different electronics. The manual advises against it, but then explains that there are extra wires for adding things, that the factory put in, strapped up under the dash. I'd like to add fog lights, that can't be on if the lights are off. (Usually I'd hook them up to the fuse for the parking lights). I'd like to hot wire in a radar detector. (Usually I'd hook that up to an ACC fuse.) and I'd also like to install an aftermarket tachometer. If this is possible, Has anyone done it? I have no Idea where to hook it up. It's an autometer tach. Thanks ahead of time, for any info. that might help!

Also, I'd like to put in a small amp. and subs, but leave in the factory stereo, which happens to be integrated into the whole car.