Mm1040 in .5 cubic feet box

So I am custom fabing a false floor in my g35 trunk area to replace where the spare tire went.
The amps and everythng else will be under the trunk carpet with the only thing visible being the top of the sub and speaker grill.
After doing everthing I could to buy me the most space possible for the box I only came up with something that will have around .5 cubic feet without the sub.

What should I expect? I listen to mostly rock/ alternative etc.. So if it loses some deep bass I'm not overly concerned..

Opinions / suggestions?
Thanks in advance.

I would build it to spec or a little larger. Even at the recommended .62 cubic feet after woofer displacement Polk also recommends polyfill to trick the woofer into thinking its in a larger box. If this speaker was on the passenger floor board then I would not be as concerned buts since its in the trunk you need the extra cubic feet. I would go as much as .9 to 1 cubic foot...