Is it safe to request more power than the alternator can give?

I have a 1997 lexus ls400 and it has an 80 amp alternator, an my amplifier for my subwoofers is 1200 RMS and I have 2 gauge power wire hooked up to the amp so it can get the full power it needs, so I was wondering if it is safe to turn the amp to full volume. I have a 600 watt sub on there right now, and I was going to add another, but I'm not sure if it is safe.