If your really considering dropping a sub into your car I wouldn't go for a false floor or boot build or anything like that, keep it simple, sub box built right will work wonders, also a vibe or alpine sub is the typical sub a person who doesn't really know much about audio will go for, if you want something bespoke, something with noticeably different sounds i'd go for a kicker l7 or a db audio sub, they do cost a lot but you get what you pay for, I have ran a 15" kicker l7 and I currently have a db audio t-rex and the sounds are incredible, get the box made right and tuned well and you won't look back!