If you were to use a car sub for home theatre use what could you do to get it to work/sound like a home sub,build a bigger box?or maybe build something around it?Is it even possible?
Yes it would help. Your room has a much lower resonant frequency than a car does so you need more reinforcement down there. Tuning a box to a subs FS is going to make the output at that frequency very strong but it's going to have a big peak, probably not a bad thing in your home.