There arent any standard connectors on the back of the basic Fiat headunit. I changed the standard tape deck for a Blaupunkt CD head unit (only 85 quid) and went from there. Bought a JBL amp and 12" MTX Sub, with my own custom box. Even tho the the BP headunit didnt have standard Phono inputs in the back, it is still possible to use wiring clips to attach it to the relevant wires. The wiring was easy enough, taking the wires down the passenger side and up thru and round the back of the glove compartment. The most difficult thing was getting the positive lead from the amp thru into the engine bay. After a few minutes of fiddling with a screwdriver, the wire was thru. I guess it is possible to do the same with the standard head unit, but i personally would recommend getting a dash adapter and getting a better CD /Tape deck first as the standard one is pants ;p