Hi,

don't use the stock wiring harness to connect you new amp. Drag new plus and minus wires directly from the car starter battery and use a main fuse for plus that schould be near the car battery. Also use this new wiring for you new head unit. Best is to use a distribution bliock for car hifi components.

For the installation of you new Kicker subs drag new speaker cables from the amp to the subs. Don't use the original wiring.

The original wiring was made and dimensioned for the relatively low power oem amp.

Regards