Summary: I returned this because the size is not the normal size of most tens (in my experience). I can't speak for the sound, because it didn't fit my box. I gave it three stars because I am not sure about the sound, it did appear to be a nice low profile sub though, just be sure to get the box that Pioneer sells...
Summary: Chose the shallow model of the sub so with the self-assembled enclosure(using recommended dimensions from manual) it won't take up too much of the boot space in my Hyundai Avante 2009(aka Elantra HD). Ran it through a Pioneer GM-D7500M mono amp and Kenwood X396 head unit with dedicated front, back and subwoofer RCA outputs. Used Polk D651s components for front speakers and D651 for rear powered also by Pioneer GM-D9500F 4ch amp.
Summary: I'm not very experienced in car audio but I purchased this and am satisfied. I built the box the instruction manual calls for out of 3/4 inch MDF and it fits perfectly behind the seat of my dodge dakota quad cab. Bass is good. You aren't going to be shaking down the house but it's great for what I wanted, something to make my music sound good without looking like a 16 year old.
Summary: I was looking for a nice subwoofer to fill in my audio without draining my bank, or sounding like an idiot. This sub is perfect for that. I don't have much experience with subwoofers, but this has a very solid metal construction, and molded plastic cone. I am using with a 300w RMS JBL amp, and it is a great combination. I am very happy with the audio quality of this sub.
Summary: Put this in my GTI with a custom fiberglass box with .55 cu ft. of air space. Paired it with a Rockford R250X1 mono block. The two ohm draw of the speaker pulled maximum current from the amp. The amp actually came pushing 315watts at 2 ohms so it drives the sub pretty hard. This sub was extremely shallow and still provides an very good deep bass as well as hard hitting bass while in a pretty small box.
Summary: I built a custom sealed down firing box for this speaker. I am powering it with a 500 watt 2 Ohm alpine. PERFECT!!! I am not sure why some reviews are saying that this speaker misses the deep bass notes. My set up hits amazingly hard and low. I have only had it hooked up long enough to break it in, but so far it provides more than enough bass. Great product. I do not know how long it will last, but this speaker is built very tough.
Summary: It shakes my car if I turn it up. I am a bit tentative but so far it really thumps. It is starting to expose the weakness in the separates that I have. i bought the enclosure for it and together they take up very little space. Speaker is really heavy and sturdy and impressively built. Never knew Pioneer made such good speakers. Have it hooked up to a JL Audio...which is tuned for minimal distortion with a volt meter.