thats the confusing part...hes saying form in the car it sounds louder etc so to me its sounds like sound pressure within the boot and cabin and the difference when the boot is open and pressure released well more so then when the boot is closed.

I dont see how its cancellation but wont disregard it as I see where ya comin form....cancellation and phasing tho should be reducing the perfomance of the subs and how they are heard within the cabin if this is occurring....as when the boot is opened theres more area for sound to be lost to the greater "air area" and less deflection for the sound waves as to when there in a sealed boot.

hmm good one to have a think about but yeh....still unsure yet as to wat could be the cause.

How about you learn some forum etiquette before responding to me in future. How would you know what i've heard?
For competent installers it's a commonly known issue with sedans. Depending on how well the front of the subs are sealed off from the boot will determine how much difference there will be when the boot opens. You can reduce it to virtually no difference by sealing off the boot area so no sound pressure can get in there.

Some more info:
http://www.fastfoursforumscarclub.com/t ... faq.asp#24

http://www.clubknowledge.com/mr_b/2.htm - At SUBWOOFER PERFORMANCE section.

http://www.the12volt.com/installbay/for ... ?TID=49234

http://audioforum.termpro.com/cgi-bin/u ... 8;t=012370

I agree with Stone. If i have my sub facing forward its like its not even working! but if i have it facing the rear right behind the back seat its the same deal. If its facing the rear ontop of the spare wheel its the sweet spot.... So positioning is everything as a cars have the worst acoustics.

It's just one of the issues that many people have.
I have two twelves firing towards the cabin behind a gas tank and it goes very loud, but strangely when the passenger door is opened it sounds much louder.
Saying this i don't think it has anything to do with pressure inside the boot.