Go to your local best buy...
Walk into their car audio section.
Go into the "sub" section.
They should let you pick which subs, with which amp, with which 6x9 component speakers. For the audio illiterate, its a place to stand on.
All at the push of big red buttons.
They encourage you to turn it up too...
You can also from the main switch panel go thru demos of each type of music to see which ones suit what type of music.
Me and my woman say, Rockford mono amp.
Two puch 10's, vented box
Now I tried a single punch 12, a dual box with 2 10's, power acoustik <-- can't spell that. And misc amps and configs.
The 2 channel Rockford amp was nicer, but not by THAT much, and still let some background noise in. The mono gave you the thump, without trying to play the music at all. It hit cleaner too. Not to mention was $400 cheaper.
The power acoustik stuff was all garbage. The punch 6x9's sounded better by themself.
I'm NOT a stereo guru either. Luckily my buddy who used to do db comp, will install, and supply whatever I want.
I know JL audio stuff is great too. If I bought a single sub, it would be JL.
With a glass hatch back to bounce it off of...
It won't take much. Go for clean sound. The car will do the rest.
I've been in a CRX that could bang Rammstein hard enough to stand your hair on end. It felt like it would push you thru the windshield. Hatch back.
My friend ran a 6 12 sub wall in the back of a 97 neon. Neodome horn tweeters, 2 full component sets, plexi windows, and you couldn't even be in the car when he turned it UP UP. It would burst your damn head.
I let him do my audio.