As a correction to Bigkzilla, those subwoofers amps (2) as in the diagram, are located above the driver's side kick panel...not in the doors. They are bolted to the car body. There is one for each subwoofer...left and right. Each amp has an electrical connector (as in diagram) at both upper and lower ends of amp.
The Shaker 500 system has 8 speakers total. Two rear, one subwoofer in each door, an additional enclosure in upper portion of each door with two speakers in each.
As others have said, I would expect you'd need additional wiring harnesses to complete the Shaker 500 system.