Seriously though.
The SPL/DB competitions that are held all over the USA are just amazing. The amount of sound that comes out of some of these vehicles is just overwhelming.
You can be 100ft away, and watch the hairs on your chest move from the sound.
When the competition is held, the Deck (stereo) is usually placed out of the vehicle a certain amount of feet away, or is operated by a remote. To sit inside of these vehicles without hearing protection, can and will damage eardrums. You saw in one of those videos of that girl/guy's hair moving. imagine the sound pressure of 10 fold doing that to your ear drums. It's really amazing the air pressure or displacement some of these 12 or 15 inch woofers can do.
Looking at some of these vehicles, they aren't even street legal anymore. They come in on trailers most of them. the Windows, especially the Windshield, are Thick Plexiglass and pop riveted or bolted on. Some of these vehicles run multiple Alternators and Batteries. Huge Capacitor Banks to deliver the quick power needed for when those multiple amplifiers draw power for when the bass notes hit. If you look in one of the videos another member linked, you can see the windshield vibrating and moving like an inch. You can also see that same windshield has duct tape all over it. LOL
Alma Gates, rest her soul, what an old women who was seriously involved in alot of these competitions. I remember one competition I went to, where her vehicle hit over 185db. That was many years ago. I'm sure today, vehicles are louder then that.
But, on the flip side, these competitions don't just offer SPL/DB competing vehicles. They offer vehicles competing against each other for sound quality, and some of these vehicles are just, well, just WOW! Listening to some of these vehicles, makes you wish you could go drop $30,000 on a system for your own vehicle, the sound is so clean.
I had a vehicle that was pushing 6000 watts. I had to run a second battery, as well as a dedicated high efficient alternator to keep the system going. As a precaution, I used an RV relay that turned off connection to the vehicles main battery if the ignition was turned off, that way, If I had i had listened to the stereo to long with the ignition turned off, I could still start the vehicle when the battery had run dead.