Tom Nousiane is a well respected bassaholic who reviews equipment for Sound and Vision Magazine. You can find almost all of these subs that are on this list on Sound and Vision scattered throughout their equipment reviews. This is just a compilation of those subwoofer reviews over the years in one place. His methodology and equipment used are top notch. The nice thing about the list is that all of them are tested under the same conditions (read as same room), unlike most reviews of subwoofers\speakers. So, although they may not reflect your room performance, it does provide a level playing field to compare products. A BASSE line, if you will!!!!!
What you will find, or not find, depending on your point of view in a lot of subwoofer reviews is a limit to the amount of distortion that is allowed while publishing subwoofer frequency curves. I do not intentially want to burst a lot of peoples bubbles but the limit of allowable distortion in these tests conducted by Nouisaine will answer many peoples questions as to why some of these subs are ranked the way they are.
I know this will stir the pot and a lot of people will not be happy with some of the results but do not question Mr. Nousaines approach or methods. They are beyond reproach and if you do a search on his name, you will find many manufacturers that discuss the results with respect and complete appreciation with him openly and without question.