I'm running 0 AWG from the battery to the trunk's distribution block and 4 AWG to each amplifier.
My theory is if the amplifiers can handle 4 AWG coming in, then use 4 AWG. If you starve your amplifiers, they'll get hotter quicker.
I'm not saying your amps wouldn't perform with 8 AWG just fine, but since you have the option go with 4 AWG to the amps. You won't regret it!
My Soundstream amps give me the option to run 8 AWG or 4 AWG through the use of a sleeve that downsizes the terminal diameter. However, since my Soundstream Class A 10.0 is pushing a 1000 watt load at 1 ohm, I made sure to run 4 AWG to it. Then I thought I might as well run 4 AWG to the rest of the amps as well. Works great! If your running the amplifier into a 2 or 1 ohm load, I would definitely go 4 AWG.
Having an adequate electrical system is crucial as well. Make sure all of your connections are secure and well planned out. Make sure your battery is in good condition since this adds strain to your electrical as well. Remember, your battery is a load on the vehicle while the car is running. Upgrade your factory wiring under the hood. This will make a tremendous difference!
