Ive dont the big 3 i have a 240amp atl. 0/1guage wire battery un the back red top up front went from 2 hifonics 1200 rms amps to a crappy 3500 diesel audio not rated. Why please help
This is a good place to start. Your stock electrical wires were not meant to accommodate that kind of power for extended period of time.
Also, make sure your grounds are bolted tightly to unpainted chassis. That usually means grinding off the paint down to bare metal. Use the same gauge as the battery connection or larger.