you cant physically slow down a sound wave ... it travels at the same speed (330m/s) no matter what frequency. its the time it takes to get there!

for example. sound travels at 1 foot per millisecond (1000 feet = 330m/s)

a 1khz tone has a wavelength of roughly 1 foot in air.

from this you can deduct that to hear a 1 second delay from applyign a 1khz tone, you would have to be 1000ft away.

your thinking of padding out the enclosure which will fool the subs. remember if its .65 without the sub it, its probably going to be around .45 to .55 with the sub in!!!

i worked mine out at about 1.1 1.2 cuft without sub displacement which is around 0.2 ... so it worked out quite nicely for me.

the box i have in my 740 is huge, takes 2 people to lift with subs in and wont fit in my 940 for some reason though the hole looks big enough!

Matt