He means FI Q. a type of sub.
You are looking for a good sql (sound quality level) sub
RE Audio XXX, new and old version
Image Dynamics IDMax
FI Q
Adire Audio Brahma
Ascendant Audio Avalanche
SoundSplinter
Really you can get a lot of subs that hit the lows, the xxx owns the lows (my personal favorite). but these subs have great sq as well.
When you design your system make sure to atleast not get a prefab box. The reason why is most prefabs are tuned high and are plain. Get a nice ported box tuned low, around 30-34 hz.