putting subs inside of the car

i built a box that was to big for my trunk for a kicker l7 15 and i have a honds civic so i put the box on the back seat with the sub firing to the side of the cehicale is this worth my time or should i find a way to get it into the trunk the box is 4cuft and is moving alot of air where it is now but i feel it would be better in the trunk4 12s cvr sealed

2 hifonics bxi608d

1 kinetic hc 800

alpine reciever

infinity kappa door speakers

either build a box thats sealed that should fit in anything. or build a ported box in the vehicle. this can be tricky though make sure you think about your steps and if you can get your sub in with the box inside, etc. or you may be able to make a box thats a different shape that can fit in and out. go to lowes etc. and mdf board is about 25$ for a 4x8 sheet. one sheet should do a big box. i built two 5 cu ft boxes w 3x18x13 ports out of less then two sheets!Ben carnes-2ma hk15x2 + 5500d