U're better off with an IXL if u dont mind stretching out a tad. Well worth it, IMO. I've built a sealed IXL18 in a 107L box, circa 22inch cube, the bass extention is very well defined and very tight for a music sub. Most people advised me to go ported, but due to size restrictions, i've decided to go sealed. Its powered by an EP2500. For movies, the bass is quite tight and deep and at my listening volumes, I think its sufficient. If I do need the extra extention, i'll build another one. Took me 4 days from build. Bear in mind that the woofer needs a fair bit of running in, which may seem that its not *loud* enough, but be patient, as its gonna be awesome after the coils loosen up.
Now everytime i put on "Eye of the Tiger" track, it rocks so good, that my neighbours were keen and they came over to check it out.