With an amp in most any car i wouldnt recommend doing that at all. When an amp gets starved for power it stresses and stress causes heat and heat is car audios worst enemy.

I have a 95 integra and am running about 2600watts with a 190amp current draw backed up by a 220/240 amp alternator and 2 yellow tops in the back and 4 caps and i would not play it for 1 min without it running.

But thats just me!!!!!!!