When shopping for a car amps you will notice that the power is sometimes measured in RMS watts and sometimes measured in max watts. RMS watts in a car amp, or root means square, is the best measurement to go off of when buying a amp. This is a measurement of power that will give you a better idea of what type of output to expect from your car amps.
I have seen some amps advertised as a 2000 watt amp, but only deliver 250 watts RMS. Although an amp like this might be able to produce 2000 watts for a very brief second, an amp like this is going to be producing 250 watts most of the time. Most quality name brand amplifiers have always stated the power in RMS Watts and the Federal Trade Commission has stepped in and put an end to the false advertising of car amps making it an industry standard of how company's state the power.
Simply put the peek power is just the amount of power that an amp can handle for a instant without damaging it. RMS watts are always going to be lower than maximum power or peak power. The peak power is usually 5 or 6 times higher than the RMS power rating. Remember when shopping for car amps always compare the RMS watts when trying to decide which amp you are going to want to use.