I have installed and can recommend the Kenwood KSC-SW11. I have mine mounted under the passenger front seat and tied into the front speaker channels. I like the remote tuner for the sub that allows adjustment for the given song and also if you're using different inputs like CD vs Bluetooth vs Aux, etc.
When I was initially testing the sub, I just had it sitting loosely on the carpet, and the response was ok, but I was little disappointed. This sub has the ability to swap polarity 180, and that improved things. But, when I installed it permanently, things got much better.
I notched the carpet and used two 1" oak blocks to elevate it above the carpet and rear floor heat duct. I used 3M vhb tape to lock the blocks to the metal floor, and then screwed the amp brackets to the blocks.
I think it's important, especially on smaller subs, to make a hard connection to the floorboard. Since a lot of a sub's tones are below human hearing, the ability to feel bass in the seat of your pants is better transmitted this way.
Narat