Right I need to get something cleared up here,

Im looking to fit a sub, using the standard HU. I've searched around and some people say there is already wiring in the footwell some say there isn't unless you had a sub fitted from fiat.

My question simple is how do you install a sub plus amp using the standard HU? Is there existing wiring? If not is there an output on the HU or is it a case of taking the feed from the rear speakers?

Before anyone says use the search tool I have already but like I said there is a lot of contradicting information.

Thanks in Advance