I know I may be crossing the line with this post but does a sub always need a box? Depending on how my speakers sound with an amp I may buy an 8" sub like the Polk MM2084. There is an area about 12"x12" that's cut out of the frame in the trunk behind the rear seats and I was wondering if I could treat a sub like a coax and install it there? Space is at a premium in my trunk so this idea appeals to me. I look forward to any input. Thanks.