Okay, so unlike all the other 16 year old kids below me who say they have been in car audio for 15 some years and talk like the haven't gotten out of high school yet about this sub. I'm going to give it a fair review.
Sub is by far no SQ champ. If SQ is your thing, defiantly stay away from the R. You could try a type X, their SQ is very pleasing.
As far as SPL goes, I tested this sub in 2 different Boxes, a 3.8 ft^3 @ 35 Hz and a 3.6 ft^3 @ 30 Hz.
For daily driving the 30Hz tuning made the sub very much enjoyable, and it got low and rang the ears. the 3.8 @ 35 Hz box did get noticeably louder, but I like low tuning, especially on subs that can get low. As a hip/hop daily listener, this single 15" in the box mentioned above would be more then enough to satisfy anybody. It metered in 144.7 dB SPL @ 33 hz in the 3.6 box, and 145.6 dB SPL @ 37 hz in the 3.8 box.
The power handling is lightly skewed, as this sub can take 1500 RMS daily, assuming you are the average nimb-wit, turning the gain knob all the way up and bass boost maxed out.
I'd recommend this product for daily hip/hop listeners who want a cheap and loud single 15. Just don't forget to get a custom box built for your sub, as the box enhances the sub, not the other way around.