Ok so me and a mate have installed a new JVC headunit and have got it all working correctly including the front speakers, but cannot get the rear speakers to work. Do the rear speakers run off the AMP with this premo sound? Will i need to wire up the stock AMP with my new headunit to get back speakers? If so how do i go about this? cheers in advance guys

yeah the rear speakers and 8inch sub are powered by the amp in the boot.
three rca leads, red white and yellow(sub) on the amp end, and i think that splices into another loom to a round din type plug..

so yeh just run a red/white rca from the HU down into the boot and onto the factory amp. but remember ull need a third plug lead bit for the 8inch sub

you'll also need to trigger the amp to wake up

the factory amp and sub are s**t...just run youre rear speakers straight from the headunit..

Sub is s**t, get ur self an aftermarket one and aftermarket amp to suit... ull never be dissapointed if its a decent brand with power.

With the amp, it still hammers any aftermarket headunit's internal amp. Aftermarket headunits give like between 15wrms (18wrms common) to like prob a max or 20wrms per channnel (which i don't think is common, but i dont know) (i do know the premium sound of an ef/el the front channels are 25rms) and with the ford amp its like either 40wrms per channel or 50wrms per channel.
It might not have the pre-amp settings but if u have an aftermarket headunit (in this case u would) then u still can adjust the settings for the speakers running on that stock amp. If im not mistaken.

The factory amp is an Alpine so I hardly think it is crap, it may lack a few features and not hugely powerful but the quality and reliability is there unlike all the chinese garbage around these days.....
The power from what I understand is around 40wrms/ch which would equate to around 400w/ch from the chinese rubbish....