sounds like you could maybe squeeze 2 in. the DD page recommends between 1.5 and 2.25 for 2 8's after port and sub displacement, and the recommended port for the 1.5 cube box is about .3 cu ft, which brings you to 1.8 before subs. those 1508s are just under .05 each, so the total box volume comes to 1.9 cubes. which is pretty close to your estimate, but you would really need to go out and measure it and crunch the exact numbers to see if it will fit