That is not enough por area at all. You are going to choke that sub of air. I would use atleast 2 if not 3 and then your length needs to increase as well, you'll also lose air space. The small the box you have the more"peaky" it will be. The larger the smoother the response curve. and trunk space with a 15 is not always the best unless your trunk is huge because it takes alot of space up and resrict air space