One of my friends just got a car and wants me to install his system. He bought a Cadence 800W amp for his subs (2x Sony 12" 350W ) What size cable will I need to use for the amp? Running from main battery to trunk (about 18ft I'd guess) 4GA? 2GA? The amp is rated: 300W RMS x 2 @ 4-ohms 400W RMS x 2 @ 2-ohms 800W RMS x 1 @ 4-ohms Onboard fuses are 2x 40A I've installed a few systems before, but nothing this powerful! My system has a 450W RMS amp on 4GA, but the cables are only about 3ft long. Will 4GA be enough for this amp, considering the length of the cables? Thanks.