if your lights are flickering, it your battery, if they are dimming its the altenator. What you need to do is upgrade the "big three" basically the power wires. Battery to chassis, battery to altenator and one more but i forget which one it was Prolly altenator to chassis. Make sure they are the same gauge as your amp power wire, so the car is all running the same gauge wiring(no restrictions) try getting a deep cycle battery about £40-£200 depends on what you want to get. Powercap should help, it reduces the sudden drain on the battery as the amp pulls the power. Split charge relay is