Getting a monte and i have 18s

[krackersmacks]

So im getting a 2003 monte carlo off my aunt for cheap and i have two 18 inch re audio sx's. I only want to have my subs in the trunk. And i know that re says not to put them in a sealed box but i cant think of a reason why you couldn't, as long as the box is built correctly. So my question is should i just build a sealed box or just make a small ported box or just go ahead and buy some smaller subs?

[Airborne]

sell them and get a pair of 12's. You are going to want to shoot those subs if you put them in a sealed box...