If you are into trance/rap/techno etc.... you should really go with a sub that can handle multiple bass notes that will hit very accurate and clean, not sloppy and "offbeat".
See the problem with that is if you want it to be loud, going with a ported box would be the way to go, but when you go with a ported box for your subs you lose SQ(Unless you really know how to tune, which is not very easy).
Going with a sealed box gives the best SQ you can get, but it does not get as loud as ported.
Now if you put a 1000w sub in a sealed box, its still going to get loud, just not as loud as a ported box(box being the same size obviously.)
If you want to make sure you getting good shyt, you need to make sure you going to be putting good time into your install.
Its not as easy as just buying boxes and hooking **** up. Its tricky stuff at first. We are here to help you, and there is no stupid questions. Keep posting and ask away.
If you were just being a dumbass and goofing off, most people on this forum would not help you, however it seems like everying has chimed in to say what they have to say(which is a good thing.)
Kris