YACAT: Should I get a new enclosure?

[clamum]

Here are the dimensions of the current sub enclosure I have. It's this shape because I bought it from a friend who had it in his truck.

Would it be worth getting (or building) a new one, as far as sound quality and loudness are concerned? I don't want a ported box btw, just a sealed one.

EDIT: New picture link

 

[filmmaker]

Tripod image not working under a direct link

 

[clamum]

Uploading it to my picture gallery now instead...

New link

 

[clamum]

^

 

[minendo]

What sub and what dimensions does the sub state for ideal sound?