Well heres my predicament I have a IDQ12d4 and i have a 2.5cubft box tuned to 30hz.

My question: The box is a little big for this sub, Is there anyways of making this box seem smaller without destroying it?

 

pop the sub out and screw wood or whatever to the inside of the box, taking up space.....might be better to let someone else chime in, as I have zero knowledge of non-sealed enclosures ...but thats how I'd do it for a sealed.

 

This will work but will also raise the tuning. You can always make the port a bit longer after.