Dude, your setup should run just fine. You should notice a LITTLE headlight dimming (probly just enough that YOU'LL notice and it'll end up pissing you off... did with me), In addition to upping the wire size, I'd recommend getting a capacitor or mounting a second battery in the trunk... depending on your needs/preferences. These Electrical upgrades/add-ons will help reduce the immediate drain to your alternator/battery. I personally have 1600 watts run off my stock electrical and with my cap I haven't noticed any sort of power drain of any kind, including headlight/domelight dimming. Good luck with your install.
