This is a great point and one of the tougher parts of designing an SPL enclosure with someone who is looking at a specific tuning frequency. Someone might say, " I want it to burp at 37Hz", but when I tell them, that peaking the design at this frequency, will only yield a 6dB increase from 0 referenced on 2.83V efficiency based on the -23dB loss at that frequency with the placement and such considered in the design due to cabin loss, they get disappointed sometimes, because they have their ears set on that frequency-something that someone before told them was optimal, lol. But this is also where I have to consider placement of other areas for increasing this if they have no other goals. Can make for a tough and long design process. Some have to understand that sometimes, with their goals set high, it just wont do well. I like this being mentioned.