I have the base speakers in my 05 QC 4x4. I installed a factory 6 cd head unit and steering wheel controls. I would like to add a amp and 4 new speakers. Does anyone make a wiring system to install an aftermarket amp to the factroy wiring from the head unit and out to the speakers? Hopefully this make sense. I would like to just mount the amp, supply power / ground and replace speakers without re-wiring entire truck. Is this possible?