i would go with less subs but better ones and that would also require a smaller box and save ya a lil more $ and probably be a bit louder. you got 2kw to feed. two nice 12s or 10s or like mentioned one 18" would be better than 4 entry level 15s. if your lucky those 4 15s would be almost as loud as my two 10" re sx's. hate to see ya waste money on the something not necessary. you will find that one or two good subs will crush 4 entry level ones and it might hurt your feelings if your 4 15s get crushed by a pair of 8s or 10s.