alright so im building a box for 2 15" LI's. the box would be 33" in depth which gives me 3 inches from the hatch on my jimmy.

i think i read on here somewhere that there should be a least 6 inches for it to load off whatever the ports facing.

the subs would be on top and port on bottom.

I like to use my own rule of thumb that the port should be atleast the width of the port away from any surface so that way that surface doesnt act as an extension of the port. some people say you can use half the port width, but i like to say the full width. and i could be wrong, this is just from my limited experience is the port further away from the surface to allow it to breath seems to be better, on the meter anyways.

I like to use my own rule of thumb that the port should be atleast the width of the port away from any surface so that way that surface doesnt act as an extension of the port. some people say you can use half the port width, but i like to say the full width. and i could be wrong, this is just from my limited experience is the port further away from the surface to allow it to breath seems to be better, on the meter anyways.

x2 I use the same rule.

No matter the port I would do at LEAST 6" from the back hatch.

I just tested this today matter of fact and my score was exactly the same.

First time the port was about 4" from the hatch at the bottom and about 2" at the top (it tapers) in my Yukon. Second time I pushed the third row up and moved the box back over a foot from the hatch and there was no change on the meter, tho it does seem to move more air and sound louder to the ear. I was expecting to pick up a little but, so phycoacoustics maybe.

My .02

I just tested this today matter of fact and my score was exactly the same.

First time the port was about 4" from the hatch at the bottom and about 2" at the top (it tapers) in my Yukon. Second time I pushed the third row up and moved the box back over a foot from the hatch and there was no change on the meter, tho it does seem to move more air and sound louder to the ear. I was expecting to pick up a little but, so phycoacoustics maybe.

My .02

When the box is closer to the hatch then the port is wide the hatch then acts like another port, thus, tuning the box to whatever the trucks resonant frequency is.

I just tested this today matter of fact and my score was exactly the same.

First time the port was about 4" from the hatch at the bottom and about 2" at the top (it tapers) in my Yukon. Second time I pushed the third row up and moved the box back over a foot from the hatch and there was no change on the meter, tho it does seem to move more air and sound louder to the ear. I was expecting to pick up a little but, so phycoacoustics maybe.

My .02

When the box is closer to the hatch then the port is wide the hatch then acts like another port, thus, tuning the box to whatever the trucks resonant frequency is.

That's what I was thinking, but it didn't change my score.

My peak went up from 36 to 37hz, that was the only change.

I think the vehicle makes a difference when it comes to the full port width away from the back of the vehicle.

I just tested this today matter of fact and my score was exactly the same.

First time the port was about 4" from the hatch at the bottom and about 2" at the top (it tapers) in my Yukon. Second time I pushed the third row up and moved the box back over a foot from the hatch and there was no change on the meter, tho it does seem to move more air and sound louder to the ear. I was expecting to pick up a little but, so phycoacoustics maybe.

My .02

When the box is closer to the hatch then the port is wide the hatch then acts like another port, thus, tuning the box to whatever the trucks resonant frequency is.

That's what I was thinking, but it didn't change my score.

My peak went up from 36 to 37hz, that was the only change.

Move it back and listen to it, then slide it away from the hatch and listen to it. Sounds MUCH better I promise.

I just tested this today matter of fact and my score was exactly the same.

First time the port was about 4" from the hatch at the bottom and about 2" at the top (it tapers) in my Yukon. Second time I pushed the third row up and moved the box back over a foot from the hatch and there was no change on the meter, tho it does seem to move more air and sound louder to the ear. I was expecting to pick up a little but, so phycoacoustics maybe.

My .02

When the box is closer to the hatch then the port is wide the hatch then acts like another port, thus, tuning the box to whatever the trucks resonant frequency is.

That's what I was thinking, but it didn't change my score.

My peak went up from 36 to 37hz, that was the only change.

Move it back and listen to it, then slide it away from the hatch and listen to it. Sounds MUCH better I promise.

Oh I agree with you there. It moves more air too, IMO even if the meter does say no.

In a small hatch, moving closer to the hatch flattened the response.

But it's going to depend a lot on the actual box size and the car. I'd build it with plenty of room between the tailgate and the box.

buy a termlab and test it thats the only way to be sure