Trial and error is what people do when they dont understand the math involved. Its pure math. Engineering is available to everyone (almost) for a very small fee actually. When a manufacturer states that the sub is "best in this or that type of box", they really are broadcasting that they dont know. There is nothing wrong with that either, but they need to just say it, admit it, whatever they want to call it. Dont you admit that you dont have a structural engineering degree, therefor you cannot construct a hybrid suspension bridge to replace the golden gate bridge? Of course, and it doesnt hurt your feelings in the least. The math involved in that profession is definite, there is no guesswork....only math. The construction/assembly techniques are already there.....they are not guessing. There is a service available with all the defined math already there. BTW, the information (to learn) is all out there also, but of all the enthusiasts i know out there, none love it enough to do what it takes to learn everything required to truly engineer enclosures for exact response curves at a specific target listening position in a defined, contained environment.
For a quick analogy as back-up info: if u sit in your living room, center of your couch....have your buddy move your subwoofer around the room to different locations and you easily notice the response is different at every location. The manufacturer of that piece had to choose a single enclosure, but knew it would sound different in EVERY application.....yet they bother to give you response specs at 1w/1m as if they apply to your room, your sitting position and your sub position. The same thing applies to the vehicle, just that small interior shape changes affect the response more drastically. Trunk or SUV, that is like adding or taking away another whole chamber of a bandpass enclosure. Ported or sealed is not the real question. The question is, can i get the desired results with my available sub, power, vehicle, listening position, max box dimensions and box location? Whatever type of box alignment it takes to get that response is what it takes....a manufacturer recommended ported box could utterly fail when it could actually be a single reflex bandpass that does the job perfectly.....but the manufacturer says the EBP or QTS numbers mean that it wont work in a sealed box of any sort.
