i keep my box 5-6" from the back. but then again my subs fire up...//content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif
personal prefrence is to have the subwoofer diameter from any surface, if you are just worryed about the sub actualy hitting the back of the trunk, look at the specs of the sub. the one way excursion of the sub is usualy stated in mm.
i keep my box 5-6" from the back. but then again my subs fire up...//content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif