Well ok, the stereo is rated at 52w per channel, but also says 17w per channel rms. The old speakers in the rear are 100w max, but don't have an rms rating on the label, so, by comparison with other speakers in the same max rating, they are probably only about 30-35w rms. Which is fine at equal fade, but I can't hear them up front like that, so I fade it to the rear and change the settings to have better sound etc. And that's when the rear speakers pop at volume. So, I bought some pioneer 3-ways with 300w max and 50w rms and plugged them in and turned it on. I got real scared for a second cuz all I heard was treble. Then I held the speaker in its mounting position and felt much better. Didn't realize that space acts that much like a speaker box. Ok, so, they sound great and you have to turn it almost to max volume before they start to fuzz or pop. Done with that. Now, the radiator. They called back to refund me. Apparently, the csf copper rad is no longer made. So I ordered the performance brand for 30 bucks more. And 3 rear brake hoses for when I put the springs and spacers on to lift her up.
17 watt RMS (root mean square) is the continuous amount each channel puts out. 52 is the max per channel it will put out which typically occurs at higher octaves.
Under driving a speaker (too little power) will cause damage just like over driving (too much power).