Hi. Help to design please vented box for 2 Ground Zero GZRW 300x. For SPL.

Datasheet sub:

Radioactive GZRW 300X

The sizes of a luggage space:
33.4x21.6x19.6 inch

Fs of salon of the my car 48-55 Hz.
Russian bad car Vaz 2112.)

For quality 90 litres pure have I have turned out. On 35 Hz.

Help me calculate the housing to the maximum pressure.
On SPL on 45-50 Hz?

We will have competition on SPL.
First, for the first time in our small town.