I own a hatchback with a shelf running from the top of the back seat to the bottom of the hatch window. In this deck/shelf I have 4 6x9's mounted. If I place my enclosure under this shelf with the drivers firing upwards toward the 6x9's will the air pressure movement cause interfearance, or worse, for the 6x9's or will 400 watts into the subs not be enough to cause a problem. The distance between the enclosure and the cones on the 6x9's is about 18". I just don't want my system fighting itself even a little. I listen to all types of music and get very little to alot of bass.
Secondary question, will this setup affect the potential of the subs. Firing them toward the back seat is a possibility but with no headliner I was really wanting the upward firing. However if SPL or SQ will be affected I'll go however it's recommended.
Thanx in advance for any help