after you recommending 3^3 per sub I'm wondering the same thing. 4th order is nothing like a regular ported box. I've tried the AQ's in 3cubes each last year and it didn't work well at all. VERY peaky and didn't get low. AQ/DD subs like BIG enclosures...i also have AQ subs .... 2 18" AQ HDC 18's with aluminum coils in a 4th order ... pretty sure im not a n00b.
4.5 is a hair big per sub. id do more towards 3 cubes per, but what do i know.
otherwise .... the box looks great. and the products are great as well.
only 1 3500?