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
+3 or+4 for Vandy 2Wq......2 of them of course :^)
I've had REL Stadium II and there is no real comparison.
Fast, clean, deep and most importantly.......leaves the signal to the main speakers absolutely pure and untouched.
I have owned the Vandersteen subwoofer and it is very good. I like how it connects to the system relieving the amp and main speakers of the lowest frequencies. However, I feel the REL is better and is much simpler to connect and dial in to the system. The REL does not sound like a subwoofer it makes bass music.
I am currently using a REL T5 with my SF Guarneri Homage speakers. The GH's are lightning fast, the REL is a very good match, if that says something about their speed. Depending on room size, I would highly recommend the T5 if one is using a small to small/medium size room.