My spare tire well is a U shape with the top of the U being a flat surface at the rear of the car. All the installs i see are with the sub facing up, has anyone tried facing the sub toward the rear? Was there a a gain? i was thinking with a gap of 5" roughly and with a surface for the sound waves to smack i would get noticeably better bass than facing the sub up. Its a Massive Hippo 84 sub and im doing a ported enclosure. I was going to face the sub and port toward the back, has anyone tried variations in sub and and port direction and tested them? Here is an illustration, any thoughts?