i take FI BTL N2 Ported box: 4.5-8.0cuft | 4.5-8.0cuft Sub OD: 18.500” | 18.500” Cut ID: 16.750” | 16.750” Mounting depth: 11.125” | 11.125” Displacement: 0.18cuft | 0.18cuft that i need box design 8.0cuft and how many turned recommed ported 32Hz turned right any services provide heliping making box design subwoofer prefer US easy