There is a difference with car audio subs. If you want SQ, you look for a sub with those characteristics. If you want to rattle your neighbor’s windows, you look for that. Seal boxes tend to be more musical as well. Thinking of boxes, careful design and fabrication is a MUST. They need to be rigid with the appropriate amount of volume for the sub you buy. Each sub will come with cubic feet requirements. And then of course power is another consideration. Amp design is vastly different. I wouldn’t go cheap with the amp.
My last install was around four years ago, and I have not kept up on car audio since then. When I did install the system (03 Dodge Quad Cab P-up), I used two, 10” Soundstream Van Gough subs and built my box out of 3/4” MDF with internal braising. I went through several different amps and ended up with two, 500 watt Phoenix Gold mono’s. The combination was very good. I think you can find the subs for under $150 each now and the amps can range anywhere from $200 to $400. I also opted for an Optima Yellow Top deep cycle battery and a capacitor for each channel. Some folks tell you to run a new alternator, but I disagree with that theory. Don’t forget running good wire and connectors. #2 depending on the amp current draw, or possibly #4.
You should also consider Dyno-matt everwhere you can. Just that alone can make a car's audio come to life.
