I am thinking of building a subwoofer for my car, the only problem is my car is a mazda miata. There is virtually no space inside the cabin, so i was thinking of placing the subwoofer in the trunk. Being that the miata is a convertable, much of the sound will be deadened before it reaches the cabin, especailly with the top down. This is basically a waste of my time. I then began to wonder about the working of a tuned ported box. I know that the port length is used to determine the frequency of the box, but does the port have to be inside the box? I was wondering if i could build a ported box, and then run the port hole directly into the back of my car through my trunk. That is, have the length of port tubing outside the box, and running into the back of my car through the trunk wall. Obviously this would require a bit of handywork, but would this work? If anyone knows, let me know. I think that would be an interesting project, and an easy way to get some subs in my car.