so I just got my single XL 18" a few days ago and just started using it today and my box is tuned at 29hz now I do give it this it hits WAY lower than my 2 level 3 15s but the highs/SPL isn't a loud I know its 2 15s vs 1 18 but I think it has more potential so what would be the tone/hz that would do the most DB in a 29hz box?