Stereo & Electronics - sub box too big?

i have a 10'' alpine type-r in a 1f^3 sealed box, the manual says that the sub works best in a sealed box from .5-.8f^3, is there anything i can use such as polyfill to make the box seem smaller? or am i missing something?

Polyfill is used when a box is too small.

You can cut and glue boards to take up some of the airspace.

rotwiler is right, polyfill makes lowers the Qtc of the box making it seem bigger then it really is.