1300 watts RMS is PLENTY. 4000 watts RMS is really overkill. Whats the point, so you can blow out your ear drums and go deaf at 30? So that people a block away from you can hear you coming? PLEASE don't tell me because it sounds better.
I worked at a pro shop from the age of 17 until i was 24. I couldnt even count the number of systems i have designed/sold and installed. If you were competing for volume, I could understand, but driving on the same road that I am, while blasting your stereo at volumes that will prevent you from hearing the oncoming horn, or the scream of the child you just backed into is irresponsible and a danger. Moral of the story, I'm against 4000 watts into your vehicle. You fell prey to stereo salesman who make you think that more is better. You could have a clean sounding system with less than a total of 1000 watts that will still get you as much attention. It will make up for penis size just as much as the 4000 watt system.
Off of the soapbox... When you drive an amplifier at a low impedence load, it draws sequentially more and more amperage. The point of such amps were designed as ways to get around wattage classes in competition. Running your amplifier at 2 ohm load will save you substantial wear on your charging system and as a matter of fact, If you can do it, take a look at getting a 4 ohm load to really ease things.
If its volume that you want, pay more attention to the efficiency of a sub than its power handling. You need to increase your wattage 10x to double the volume of a sub (4000 watt amplifer is only twice as loud as a 400 watt amplifier) where as if you were to select a speaker that had 3db more sensitivity, and run it on 400 watts, it would be the same volume as the lesser sub with 4000 watts.
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