well after i thought i had my design complete, actually i have the box pieces cut out, i figured the port size wrong. i didn't have enough room to go with a slot style so i settled on a single 4" aero. now after reading and questioning myself for the past few days i asked the question on the SSA forums. i have a single Fi SSD15. so, a single 4" will not yield enough port area for that speaker. the box is currently designed at 3.5 cu ft after the speaker displacement and the single 4" port. so, my question is what creative ideas have worked for people? my thought is to port the box out the bottom (3 - 4" ports), down into the spare tire well, 90 them and continue back to correct length. does porting the box externally work? the sub is firing into the cabin of the car and will be sealed off from the trunk.