Summary: I purchased this 2 1/2 years ago and installed it myself. While it did add bass to my system it is still not very powerful. I drive a buick century and I ended up placing the speaker in the back seat because it could not be heard while it was in the trunk. This is definitely not a very powerful system but it does add adequate bass for what you pay for it. I see that the price has gone up because it was only $50 when I bought it.
Summary: This item is pretty low-end and I would have rated it a 1 except I was able to use the enclosure with another subwoofer and make a pretty decent system. The amplifier is a 500W max amp, it doesn't say what the RMS is and I found it to be pretty pathetic. The subwoofer contained in the enclosure is about as cheap as they come. I was hoping I could include a picture of the unit disassembled so everyone could see how cheap it was.
Summary: For the price its not that bad. Was hoping for something a little better though. The materials used for amp part seem a bit shoddy. If something in your trunk hits it the wrong way the knobs can easily break off must practice caution when placing things around it. Also, there is no fuse on amplifier part which I thought was odd. I don't expect it to last very long but for the price its not to risky or wasteful.