they are perfect 10s single voice coil I have video of them in action and I love them and will never ever ever get another sub unless its another Kappa perfect 10. these ones are 4 years old and still perfect. The distortion you hear in the video is the cameras mic cant handle it. They make no distortion at all. You need them. Only 1 will do but 2 is great. Think a third may be in my future though. They are sooooo clean.
The cover I got at the dealer.
Link to the Vid.
http://yrethguad.tripod.com/ the last 2 are both funny one is my car and one is just damn funny.