ok i got a dc 3.5k amp id like to stick with not sure of my sub decision i currently have a new dc xlm2 15 sounds nice on a 3.5k but i want louder im decideing between grabing 1 more xl 15 or 4 lvl3 12s .or 2 lvl 4 18s cant decide. i have room for either as its a 99 gmc sierra ext cab with back seat completly removed and a flat deck built in place of it looking for advice from people who have seen it all