I got close to that setup with the 8w7'* but they were a little shy on output.. if i had a pair of 13w7'* im sure i would slow down alot... i actually thought about make the whole trunk a box and mounting a 18 inbetween the rear seats facing inward but we will eventually sell this car and no one will want to buy it with a big hole in the backrest

Thats why you go to the junkyard and get a spare one

Makes sense to me, my trunk is my box. hehehe