How much space should i give me Sub

[uzy]

how much space should the sub have before it hits any obstruction, my bos design will mean that i will have 3" of space before the tailgate, would this affect the performance of the sub in anyway.

will i get better sound if i mount the sub on the top of the box and have the port facing forwards, but then i would have 2" space before the parcell shelf which design should i use??????

[billy18bm]

dosent mater as long as it wont hit it id would just make sure @ the subs max excursion there is at least an inch or two... and the to the upfiring question whats above them....if it will rattle dont.. becuase it sounds like ****...