I don't think it's worth trying to wire it to the "factory" system. The "factory" system (in my car at least) consists of one speaker in the center of the dash. I have to be honest that it sounds pretty good for being over 30 years old. Besides the speaker, I think there's one small power cable and an antenna. That's it. Nothing to really run an Empeg on.



My suggestion is to install an amp under one of the front seats (this is how mine is). You can then run the wires under the carpet or along the side of the car to the front. A couple different companies (including Pioneer) make some nice speakers which install as kick panels under the dash. This will give you good sound without having to do any modifications.



Here's a couple of websites where you can get Mustang parts:



http://www.ilovemymustang.com/

http://www.orangecoastonline.com/mustang.htm

http://www.restoremustangs.com/

http://www.karmustang.com/default.html

http://www.larrysmustang.com/

http://www.l-i-mustang.com/index.html

http://www.mustangsunlimited.com/



Quite a few of these will send you a free catalog.