Most vehicles are generally louder with a door open, window down vs the vehicle being sealed right? Depending on the db level is there an inverse effect and a sealed vehicle is louder? Or does it just depend on the frequency as an open door would make the cabin part of the enclosure (4th order?)

I know there's different sanctions and different rules among classes, so certain cases I'm assuming the vehicle has to be sealed and can't have any windows/door open.

So if my first theory is true, then why do people seal every air leak in their vehicle to gain dbs? Wouldn't they want places for the air to escape (like an open door, just not opened quite as much).

OR would this^ be like a leaky sealed enclosure compared to a ported enclosure?

Some things just seem contradictory and never asked

All depends on the vehicle.

Most vehicles are louder door open or something venting.

Extreme vehicles are loud because they have ZERO air leaks and ZERO flex.

Yeah extreme SPL is, well, extreme. They have insane amounts of pressure in the vehicles and if they lose any of that pressure their scores go down, these are the undrivable vehicles filled with concrete, they are made for one note ant to be completely sealed legal..

There is a rule in audio, I can;t remember what it's called, lol, but it's the smallest space in a subwoofer system will always be the loudest(easier to pressurize due to less airspace). So when your venting, outside the vehicle becomes the largest space, and depending on the setup your vehicle cabin, or internal volume of the enclosure will be smallest and second smallest, that combined with a bandpass of sorts makes outlaw scores loudest.

All depends on the vehicle.

Most vehicles are louder door open or something venting.

Extreme vehicles are loud because they have ZERO air leaks and ZERO flex.

My Lumina was loudest sealed up and on the dash

Driver door open window up w/ passenger door closed with window up for me

Driver door open window up w/ passenger door closed with window up for me

Yeah mines louder with driver door open, I have to test both doors open and see if I can tell any difference. Kinda hard without a tl

You want to be able to control where the air is escaping, and you only want it in a small number of areas. It's kinda like a box. Leaky box will give bad results, even though there's a big hole in the box for the port. If you have a leak in the trunk, that's pressure that's being released back there and not sent into the cabin of the vehicle, where the mic is.

Also, most SPL organizations take SPL measurements with the car sealed up. Any leak at that point would be bad.