Fastest subwoofer?


Hello, I would like to buy a subwoofer that complements a pair of very fast speakers. I know very little about subs since I rarely used them, and I am wondering what are the models that are considered to be extremely fast and good, no matter at what price point. Thanks.
ggavetti
very interesting suggestions...does anyone know paradigm millennia? i heard good things about it but i am concerned that in order to make it so cool-looking, they gave up some quality. thanks.
another vote for vandersteen...

i've owned subs from velodyne, jl audio, and now vandersteen. the vandy subs get my vote for doing pretty much everything right in my room - my system is 2 channel audio only, not HT, so like always, YMMV.
Vandy 2wq is great and probably super fast since it has implemented Feed-Forward Error Correction, but may not be powerful enough depending on the room. If mono sub's not enough, I'd get 2x2wq that could be purchased for less than $500 used