Hi,
I have a Fiesta Si aswell, and run this site - www.fiesta-si.com. But for your stereo, there should be 2 multiplugs behind where the stereo goes. If you have an aftermarket stereo, you will need to purchase the correct multiplug adapter from Halfords or the like. This allows the Ford connections to be plugged into the back of the stereo's iso plug.
Des, April 2006