Wiring

Honestly I doubt anyone actually looks at this blog yet, but I'm confused as to if I should use 4 or 8 gauge wiring for a 2000 watt amp pushing 500 watts rms to two subs. I'm planning on just getting a little kit (http://www.vminnovations.com/product_7185/Bullz-Audio-EPAK4BL-4-Gauge-Amplifier-Wiring-Kit-.html) of 4 gauge to be safe and ensure future upgrades.