I need help with box specs. I have 4 BL 15's going in a 2003 tahoe. I want to face them up( at the roof) and have these measurements; 48 wide, 28 high, 36 deep. Can someone give me a box layout or cut sheet with port measurements to make this a winner. Daily playing tuned low 29-32hz please. Thanks in Advance.

How much depth do you actually have? The top pretty much needs to be 36" deep for (4) 15's to fit. . .How much clearance is there from the back of the box to the rear door? I ask, because with subs facing up, and port facing rearward, you need room for the port to breathe.

You could do 48" wide x 36" deep x 25" high. Make the top 1.5" thick, and a few brace pieces to sturdy up the sides.

The port would face rearward. The opening would be 40" x 6.25" and needs to be 25" long (use the bottom of the box as one of the port walls). You would need 6+ inches between the box and the rear door.

Brian