Hey! A lot will depend on how much your willing to spend! I just had a 12" power acoustic 1800w sub and a kenwood 800w amp put in that i had bought from best buy! Total it only cost $300! And for only one sub it pounds with the best of em! Especially for the price! There still on sale too so thats an option! Plus there is kicker and rockford fosgate but they'll cost you some more dinero! Good decks are always kenwood and alpine!
run a search, you'll find seven billion topics and you should be able to piece together your information fine. right now, i'm running 2 orion 12"s off the stock headunit, but i'm selling those because i'm tired of bump bump thuggin'.
Come to caraudioforum.com . You'll find everything you want to know and then some. No offense to this forum but it's not specificly for car audio. Many people from caraudioforum.com do this stuff for a living. Good luck.