Alright so I've searched around the forums and have been weighing the pros and cons of keeping the stock headunit but I would like other opinions for my application.

I want to keep the headunit for the steering wheel controls and because of its steering wheel controls and how it is connected to the screen above it which contains the things such as the trip computer and gas consumption. Also because it just fits and looks nice.

However I have a elemental designs nine.1 amp and soundsplinter rl-p subwoofer from my last car I want to install and it would be so nice to just plug it into the pre-amp connections on my old alpine headunit. Plus I have an i-pod connection for my old head unit. Also I am planning on buying an elemental desgins nine.4 amplifier to power the dash speakers as well as the rear 6x9s and leave the front door setup as it is, or maybe get replacment speakers.

So is there any way to keep the steering wheel controls if I put in a new headunit? Also will the screen still display the trip computer functions if i take out the stereo? Finally is there any easy way to hookup two amps to the stock headunit without causing me a huge headache or should I just replace the headunit? If anyone else has replaced the headunit are if you are happy with it/ was is easy? I saw a kit at genuine saab for replacing the stereo is that what you used or how did you do it?

- you need a special device to keep steering wheel controls. I don't remember it's name; someone else will (or use search)
- trip computer is independent
- headunit has 8 pin DIN connector for preamp out, so you have to get an adapter or do some soldering ;)

Pac-audio makes SWI- interface cables for steering controls, but I've had less than wonderful experience with the quality of them. (Don't always work or work TOO much, etc..) You need to make sure to get the correct model associated with your headunit brand and make sure the model is actually supported.
Apparently there are a few other kits for specific headunits, that I've also been looking at.