its not the subs---the box wil be tuned to a specific number--best bet is to pay someone who REALLY REALLY does know about these things to design or build it for you. for instance -- JMAC had agrred to design my box for me.how do i find the Hz level for my sub in the box im using....its 2 rockford r3 and i want to get a ported enclosure and dont know how to filter the sound and all of that....plz help me out...tell me what i need