I have one in my boot, in the factory box, powered by a Soundstream L5.1110. I had to turn it around to face the front because it was too loud before. The kick drum was overpowering everything.
Honestly, if you want something that will shake your rearview mirror so much you can't see didley squat in it, this is the sub for you. Face it to the rear of the car and you'll feel like you're inside a giant kick drum, face it forwards and you'll think there's a bass player sitting beside you. I've never had it turned up full because my ears couldn't take it. To give you an idea of what I consider loud,the last Motorhead concert I attended, I was yelling for them to turn it up. I stood right in front of the speaker stack at my last AC/DC concert. If you want proof, I'll make a video of my mirrors while I play some Pantera. If you tune it right, it feels like Mike Tysons kidney punching you through the seat with every bass or kick drum beat. As for clarity, it's average.