Having been to Brainerd, MN years ago, for the Nationals, been to huge concerts with line arrays, and large sub systems that literally rip the air in and out of your lungs with every cycle, I still don't think there is anything close on earth that can come close to the fury of a Top Fuel Dragster / Funny Car. Possibly a pair of Danley's JH-90's in a small room with a couple of Rock Monsters?
Even up in the nose bleed section, your eyes jiggle in your head, your chest cavity resonates, and you can't begin to focus on the car during a run. It is beyond loud, even with double hearing protection. ( 33 db nr plugs + good shooting muffs )
Television doesn't even come close to doing them justice, the amount of air and fuel they process.
I have been in the pits during warm ups, and gotten a dose of nitromethane fumes. Not fun, since I wasn't prepared. Stumbing backwards through a retreating crowd with eyes, nose and throat burning wasn't cool. Getting a .090 thick copper head gasket out of Bernstein's engine, and a few pistons, one from Kalitta's engine made up for that though.
Honorable mention for "loud" at least in the HF is an un-muffled 2 stroke snowmobile engine screaming. What a crackle coming from the stingers!