A good place to look for reviews and stuff like that is sounddomain.com. once you get a handle on what is awesome, good, and crap, then i suggest going to Biddersedge.com and look around over there for the subs you want. i would suggest earthquake subs and earthquake amplifiers. but my opinion is kinda biased because thats what I use, and they are a little expensive. most companies have there low end stuff and there high end stuff. kicker subs are real nice, and they dont cost to much for there middle ground stuff. pioneer subs are real nice and so are audiobahn. but the best information i think i can give you is look around and listen to some different subs and decide what you want. and if you live near a tweeter, check them out, sometimes they have buy 1 get 1 free sales and stuff(they just had one for Xtant subs) OH WAIT. just thought of something. the company Bazooka makes bazooka tubes, they are subs in tubes all you need to do is amplify them, they arent that bad either. not top of the line, but its not crap like jensen either. if you just run one 10 or 12 inch sub, look for a amp that will put out like 200 watts bridged. if you want more than one sub, than just look for one with more. i guess thats it, sorry for makin it so long.
Adam
a.k.a. Adrock
88 Chevy Blazer FI 383
Aint nothin' like the sound of Chevy Thunder