tuning eclipse sub

Hey guys just got my car back from blowing the motor and am wanting to finish my stereo that was lift from me in may( been bad summer=$$$$). what i need is advice on the box, what would you recommend for the box tuning? paper work with the sub gave the size and hz. Here are the specs. Also this is for a sealed box.

    0.5Cuft=45hz

    1.0CuFt=41hz

    1.5CuFt=40hz

    And what are the differencesI would notice in hz tuning? Any help would be appreciated 

thanxs darin

This is a sealed box so there really isn't any "tuning" involved.  The manufacturer is giving you the Fc of the enclosure... that is, the Hz that is 3 db down from the highest SPL level, with the different box volumes.  This is for your consideration when you are allowing space for the box.  You'll notice the Fc is substantially higher when the box is small, but it stays fairly even with the other two larger sizes.  This indicates that making the box even larger would not net you substantially lower bass response.  And, if you were to imagine the 40 Hz on a curved line, the line will continue to curve downward as you go through the lower frequencies.  The lower the line is, the less the SPL is.

So, make the box either 1 cu ft or 1.5 cu ft, whatever your space allows.  The difference in the two is only 1 Hz, which isn't even a noticeable difference.  You can assume the freedom to design the enclosure somewhere between the two sizes if it fits your space best.  As far as polyfil goes, I recommend using it in all enclosures, loosely filled.