maybe its a sports feature since mine is a sport....as for that box design CRU it should slam i did one for a 12 yesterday for a jl d3 and was running a small rockford 300.1 and dude can you say 15 LOL hey cru as for that design i sent you, you can add 1/2 mdf cut them one inch by the length of the box building like a frame around the edge on both sides of the box(usually the left and right side) when done building the edge router them round. this way it give you two things ...when carpeting or vinyling the box it allow you to wrap it with one piece allowing you to tuck the extra inside the seems. then get a 1/4 piece inserting in side the frame structure allowing for carpet or vinyl thickness and it will look nice.( if you look at the pictures i sent you of the one i did in my pop up you can see the final result any questions about the frame just pm me