I'd say add 2 8" JL Audio W2's...My friend has some and man o man they hit f****** hard!!!! Plus they keep up with any techno / fast paced song.

 

Even better...i used to always want bigger subs when i was younger in high school but now i want sharper..cleaner bass if that makes sense....and 8" would probably be perfect for our cars.

also yes the JL Audio W7 are the best subs i know of...dont know bout the w2s but if JL makes them then they are good quality