The Sony XDP PK1000 subwoofer, amp, IPhone (4S and earlier) cradle add on system with Polk Dxi 400 4" front speakers and Dxi 650s rear speakers works great while preserving looks and no need to pull the head unit. $400 from Crutchfield (with coupon discount) includes amp wiring kit and rear speaker baffles. Hints: 1) There is grommet with a nipple on firewall that makes for easy passage of amplifier and DSP power wires to drivers side underdash and run back to trunk. Pull the rubber weather seal off the plastic battery/vent cover and pull the vent cover off to access-easy, no damage. 2) Pull front door panels. Loosen two top corner screws and screw under handle, pry out underneath plastic handle cover, unscrew 2 screws now exposed, and lift door panel straight up. Remove the 4" speakers-3 screws in mine, follow the black and green black wires to a plug that goes to the upper door tweeter (also green, green/black) and note the wire colors that leave the plug and go out the door to the head unit (+light green, light green/yellow striped(-). I made speaker brackets from these old speakers by cutting out the dome and supports to the speaker face, preserving the ring with screw supports. Remove the front kick panels and it is easy to see where the speaker wires are. Cut these green wires and the speaker side will be the front speaker attachment for the DSP unit whereas the head unit side will be the attachment for the audio input to the DSP unit. 3) Rear speaker replacement by popping off the plastic covers on the 3 tether hooks and unscrew the bolts, unplug brake light from inside trunk, pull rear deck forward, loosen any adhesive present. Run new rear speaker wires. Don't need to run rear speaker head unit input to DSP unit. I placed subwoofer in trunk behind passenger rear seat, amp beside it, and DSP unit about 2 inches in front of tool compartment on left attached to side with Command Strips-holds very well. the wire harnesses can go into tool compartment where all wiring can run. It is easy to find place for attaching ground wires in tool compartment also. I hooked both the yellow and the red wires from the DSP unit to the battery (separate from amp wire). Works, but I would have preferred an ignition wire for red but I don't know where to access it. Help would be appreciated.