Actually, PMPO is not Junk!!!!!!!!!! it's like this:
A speaker's power rating (in general) tells you how much A.C. power can be dissipated in the speaker's voice coil without damaging the speaker.
Honest Power Ratings:
The most honest way to rate a speaker is to give the rating as continuous RMS watts (ex: 150 watts continuous rms power). You may hear speakers advertised as "150 watt 6 x 9s" or "100 watt 6 x 9s" and you may instantly think that the "150 watt 6 x 9s" are better and will play louder than the speakers rated at 100 watts. The first thing you should realize is that speaker ratings are OFTEN exaggerated. Then you should ask if the rating is in RMS or peak watts and are the speaker ratings for instantaneous or continuous power. Most car audio speakers (with the exception of some subwoofers) are rated in peak power or music power. Only a few speakers (generally the higher quality speakers) are rated in RMS watts. While peak power is a legitimate way to rate speakers (as long as the manufacturer tells you that the power rating is in peak watts), it can be deceptive.
Peak vs RMS:
You know that peak power is 2*RMS power. If a speaker is actually capable of handling 150 watts of peak power it would only be rated to handle 75 watts RMS. If a speaker is rated to handle 150 watts 'music power', it may mean that the speaker will take only very short bursts of power approaching 150 watts RMS. Even if there are two speakers from different manufacturers which have the same power ratings, one of the manufacturers may be more conservative in their ratings than the other manufacturer. The more conservatively rated speaker would be more likely to handle its rated power. Bottom line, beware of power ratings on speakers. Knowing that some manufacturers are less than honest in their power ratings, will likely help you to make better decisions when buying speakers.