I bought this for a Saturn Vue Redline which has the amp from factory also rear subwoofer from factory,no problem connecting to new car stereo the wires are color coded to easily identify also plug and play connected easily .
I have an 04 Saturn Ion with the factory amp. The plug was a direct fit for the factory harness. A word of advice if you have the "premium" stereo in the Ion....bypass the factory amp its worth the time.