Dave, The amp is a pioneer GM-4000F 4 channel (side A is running the rear speakers with high pass filter switched on, and side B is running the sub in mono or bridged mode, with low pass filter switched on). This amp has high level inputs. The two + and two - wires from your stock sub amp are connected to the new amp's right and left high level inputs on side A or B. The sub speaker is an 8" rockford fosgate punch stage 1 (smallest available). I built the box of 3/4" poplar (poplar is a lightweight hardwood and sturdy enough for the heavy speaker). I used 10 metal screws to secure it to the doors sheet metal (no rattles) -the weight is over the rear door's hinges as well. The amp is mounted to the bracket that used to hold a rear jumpseat. I wanted better sound without loosing space or my factory radio, plus it was a fun project. I'm amazed at the sound with the factory radio and amps still working. E-mail me if you want more info. Dave
