Jackhammers are never put in large enough enclosures to perform well. PMR didn't do it, the demo truck for MTX didn't do it.... hell even the enclosure MTX builds for it themselves is grossly too small. Know why? Because if they did build a big enough enclosure for it, people would see just how impractical the thing is for CAR audio.
This is not to say I think it has any real potential. With its price tag and enclosure requirements, it would be amazingly easy to outperform it given an array of smaller and more reasonable/realistic drivers.