First let me start by saying that I am huge into the car audio scene. I ran a high end car audio store for several years, so I am in no way new to the game.
When you first take the XTEC 10" subwoofer out of the box, you will be amazed at how thin this subwoofer. Your next thought might be similar to mine the first time I held it, "How can a subwoofer like this have any output at all?". I was EXTREMELY surprised when I finally got to hear these subs.
I threw a pair into an INCREDIBLY small enclosure, only 4.5" deep total, and .5^ft for BOTH subs. What happened when I turned up the volume was incredible. My initial thoughts about this sub being unable to get loud were immediately forgotten.
For a small, compact, thin subwoofer, it gets pleasingly loud. Sound quality on the sub is also very tight and accurate. A pair of these 10"s can fit almost anywhere with their thin size and small air requirements (including under seats!) and would be plenty loud for the average consumer, and even the people who love heavy hitting bass! For the price, I don't think these subwoofers can be beat.