I am not sure if there has been a thread regarding this yet, but I am trying to find out what I would need to connect the subwoofer output connection on the back on the shaker 500 head unit to the amps that support the front door subs. My car only came with the 4 speaker system, but I have already acquired the door panels with subs, the correct cable for the door to connect to the subs, the to amps that as I am told are going to be located in the drivers side kick panel and the shaker 500 head unit.

Can anyone help me find out what I am missing?

 

You would be better off and would get far better results if you put a decent set of 8" subs in the door panels and put an amp for it in the trunk by tapping off the rear deck speakers for a feed. I don't think the non-shaker units have the pre-amp out to feed the sub amps - the harness is the same, but without the signal it will not work.