help wit subwoofer box

i made a box for a 15" sub i have to fit in my 98 civic ex coupe. its about the size of the whole trunk. i think i made the port hole too big. well thats wat sum1 told me. is there any way to fix this or wat. he said the sub sounded louder in my other car. wat shuld i do? i took me forever to build a box and get this 15 into this lil ass trunk. wat shuld i do. any suggestions?

http://www.carstereo.com/help/Articles.cfm?id=31

That should help you out.

build a new box and dont port it. It will hit harder, not as loud, but if ur like me, i like it to hit hard, not rattle everything. i vote for sealed, not ported