I need help on what box to buy?

i am about to purchase 2 12" JL Audio W3V3 and i dont know what kind of box to get. i definetly want ported i think but i dont want insane spl and no sound quality. from what i have heard, u need to get the right box if u wanna have jl subs. if u have the wrong box, there gonna sound like ****. a guy i know has offered to build me a box that will basically fill up the whole trunk of my 99 grand am and he said he is going to build it according to what the specs say about the subwoofer on jlaudio.com. it will be ported and the subs will be fired upwards in order to build the biggest box he possibly can for my trunk. is this right? does anyone have any other recommendations that would make my subs sound awesome? i know a friend who has a box built by this guy and his jl subs sound so good. very tight hard hitting b. any other ideas?