crutchfield says "Measure the depth of your subwoofer and add 2 inches. This measurement is the minimum depth of your box."

i got sample box dimensions for my IDQ12 from woodlawn cabintery and they gave a depth of 8 5/8" (external), interal = 7.125 in. the depth of the speaker based on the spec sheet is 5.8".

should i redesign my box to be at least 2 inches deeper than 5.8"?