i have a solobaric L7 and i already got it positioned in the middle of the trunk facing upward at a 135 degree angle, check my registry. but i dont know if thats the best position for a subwoofer. ive seen some pics here with the sub facing eachother on the sides of the trunk.

 

Right about where you have it should work pretty well, though you might try a little closer to the rear deck, as opposed to dead center in the middle. I've found that to deliver slightly more bass, wiht my single sub "winter system"

Summer system goes back in this weekend

 

http://www.crutchfield.com/S-Yl1hjWb...ech/kb138.html

 

i have mine pointed at the side of the trunk, tucked away in a corner.

i didn't do this because it sounds better or makes more bass....i did it for space issues. 2-3 days out of the week i have a hockey bag and sticks in my trunk so space and positioning becomes an issue.

besides, i'm not looking for crazy bass...just some clean bass that will add to the rest of my music.