need lots more information dude... what kind of music, whats your price range, you looking to upgrade or do it right first? start off with a google search and then search "the media room" on here for "subs" or "what subs"
the12volt.com has some great info as well as crutchfield.com
i recomend getting something used... got a $2500+ system in my car and paid about $1000 on sub/amps/speakers/nav/wires by buying everything except the door speakers new. all piece by piece when i found good deals.
if you dont know what your doing or talking about and you arent dealing with someone you can trust (doesnt mean someone nice at cartoys...) then just stay with popuplar brands. in order of quality/price
pioneer, kicker, kenwood, mtx, infinity, rockford phosgate, Alpine, Memphis, Boston, MB quarts, Focal, JL...??
after JL alot more shit that gets pricey
IMO if you have the money to blow go with JL amp/sub and alpine HU with focal or MB comps for a safe and popular bet. If your on a budget then go with a kenwood HU and MTX subs/amp for decent sound.
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