I bought one of AcId'* boxes a while back, and installed my two Pioneer 12" subs in them with an Infinity amp running them. I was kind of disappointed, because it really didn't put out much volume. I mean, it was infintiely better than what I'd had before(stock), just a little less than expected.
Well, the other day I picked up some PVC pipe from Lowe'* and had to turn the box sideway to use the pass through. I turned it so the subs faced the side of the trunk, to keep them from getting hit by the pipe. Got in, took off and turned on the stereo at my usual volume. Sudden audio overload, had to turn it down about 1/4. The rear view mirror was actually starting to droop as the vibration rattled it.(Tightened the set screw later)
I can't believe the sound now, I may actually have to turn down the gain on the amp itself, because if I pull the output from the radio down much more, it'll kill the sound quality.
I guess the volume of the trunk was too much for the box, and turning it towards the side cut it down to about a fifth of that volume. Kind of a loose bandpass effect, I guess.

Definitely gotta see what you're talkin about.

I think what you just said is:

you opened the pass through and it got louder.

yes?

No, he turned the subs around, so they're facing forward now, so the stuff in the trunk wouldn't damage them.

Brad'* boxes are no foolin.

I reinstalled mine today after a long winter..facing out, but hey, it was designed to face out.

Whoops, not quite. Turned them 90 degrees, so they're facing towards the driver'* side of the trunk. I think if I turned them towards the front, I might get a little more volume, but then again, maybe not. And as I said, I'm having to make adjustments to bring the bass down a little, so my mirror doesn't jump off the windshield!

BTW, I usually do have the pass-thru open. In fact, I'm thinking about pulling the door itself and putting a screen in there, that way I can have the unmuffled bass, but not have to have an ugly black door laying on the armrest, and the third brake light shining into the cabin at night.