Here are six quick quotes from Tom Nousaine that I
prove wrong in my recently published paper at
http://www.installer.com/tech/aiming2.html
read and make up your own mind...

Nousaine wrote:
Because acoustic sounds at subwoofer frequencies (approximately 100 Hz) are
omnidirectional the SPL/Frequency response will be uneffected either way.

Nousaine wrote:
I've done the experiment several times. At subwoofer
frequencies it just doesn't matter. How could it? At 20 hz the wavelength is 50
feet long so the driver displacement just pressurizes the cabin no matter where
it's placed or what direction.

Nousaine wrote:
So if your woofer is unfiltered you'll get significantly more lower and medium
midrange output and perhaps increased audibility of port grunts and driver
noises when the face of the driver is facing the listener. That's it. Try it
yourself.

Nousaine wrote:
While I'm at it let me dispell another Urban Legend. Do you get more bass with
the hatch open? Only outside the car.
Inside you get significantly less. Why? You lose the cabin gain transfer
function effect whre the driver displacement pressurizes the interior at low
frequencies delivering 12 dB/octave reinforcement as frequency falls below the
lowest mode which occurs at 60 Hz in a small car.

Nousaine wrote:
You can also read about alien visits on websites too. At bass wavelengths (17
feet @ 60 Hz and much longer at lower frequencies) there just aren't any
"cancellation" issues going on in the car cabin.

Nousaine wrote:
The only
advantage of subwoofer orientation is that facing the woofer/port away from the
listener reduces the possibility that mid-range sounds and driver/box/port
noises will be less likely to be audible.