Six

Ok, this is my Dual T-Line Design for 2 DD-508b subs. It id made to fit inside my trunk and take up nearly all the space too I have a 1999 Honda Prelude SH that I don't want to flex to death(but unlikely at this power rating and cone size), I also have very little trunk space, so I'm opting for the 2 8" subs to run at 500w or 700w at 2 ohms or 4 ohms bridged. I haven't made up my mind, but I'm leaning towards the separate 2 ohm lines, depends on the amp.

Have you considered that the box doesn't need to be a rectangle? But more of the shape of your trunk? I have attached a T-Line design that I have NOT constructed yet, but it seem to be a sound design. It was designed( of course with minor restrictions) to fit in a space that is 24"L x 26"W (for 15 3/4", then 46"W for 8 1/4") x 12.5"H. With the length of the port being about 87-88" or yielding about 38Hz tune with the Fs =37Hz of the DD-508b's I am going to use.