I impulse bought a sub and amp the other day, this is what happens when I go to pawn shops or garage sales. Anyway, I have no idea how much the cables are going to cost for it, or what kind I need. How do you work out what gauge of power cable you need? The only place I've seen selling thick power cable is Jaycar, and it was like $14/meter. I think I'm going to need like 5-10 meters.

Hah, never mind. A quick search for 'wiring kit' on Jaycar's website provided me with two suitable Amp wiring kits. I'm an idiot.

How do I decide between 8G and 4G?

Need more info to answer that, what are the specs on the amp?
Also this should probably be in the car audio section, sure a mod will move it

Need more info to answer that, what are the specs on the amp?
Also this should probably be in the car audio section, sure a mod will move it

Not quite sure, it's 500w that's all I know. Ah okay, thanks.

500watts 8 gauge will be fine, a forums search would have anwsered that for you, also theirs a post about 3 spots above yours that awnsers it also

or do my trick run a 1000w and a 400w from one 8 guage supply coz your ghetto intalling it with the scrap you have laying around then everytime you turn it up past about half way you blow the power fuse :) YEAY for cheap fuses from ebay :) (seriously i have like 10 in my glove box)
Gonna have to get around to putting some 0 guage in there.
So yeah 8 guage is fine...............
Oh and 5 metere is plenty to get from battery to boot with spare left over