I'm not all familiar with clarion. My favorite car equipment at reasonable price ranges in kenwood.
Also, the *hitting harder* has a lot to do with the settings, the song, the quality of the song, the cable. Plus it may not sound distorted, but if the excursion was big, the woofers were likley lagging behind the signal, you just didn't notice.
What I am saying is, you may think it wasn't distorted...but if you listen to the same song on a high quality system with no distortion, and compare them, you will have a reference of comparison in your brain and then will be able to tell.
His amplifier may also be different/better. In addition, the trunk of the car matters (if we are speaking of car audio). The acoustics of it matter a huge amount, and the enclosure matters a lot. Sound is pressure in air so the environment makes all the difference.