LOL MODS NOT ALLOWED IN VERSUS ANYMORE BTW
You can use the command snd_restart to stop helicopter, plane, fireworks etc. but it also mutes in-game voice chat.

Most of these are for getting rid of annoying and/or unecessarily loud sounds/visuals. I suggest using all of them but, yenno, it's up to you or whatever.

• I hate laugh cuts out both death screams and laughs. gg bm voiceline spam
  
  
• no rain(sound) cuts out noisy-butt storms. Considered mathacks (soundhacks?) depending on who you ask seeing as how you can actually hear during storms, I guess. I see no issue with it seeing as how SI are silent anyways. ¯\_(ツ)_/¯
  
  
• Silent 'Copters cuts out helicopters and planes!! Is a godsend on Dead Center, Dead Air, No Mercy and Parish.
  
  
• No fireworks sounds cuts out both firework boxes and stage fireworks. The Dark Carni finale is now a little more tolerable.
  
  
• No Music, Just Cues cuts out all music except Dark Carni finale unfortunately so I don't use it but lets you hear Tank and Witch music without all the other background nuisance.
  
  
• muzzleflash light disable Now you can play in the dark without having a seizure. Apparently mathacks but I don't really care. ¯\_(ツ)_/¯
  
  
• Adrenaline Post Process Optimiser = MORE FPS
  
  
• Softer Infected Vision Now you can play in the dark without going blind!! \o/ Or just delete whatever files in the correction folder.

The rest are personal preference. I mean, they're all personal preference but I think you get the idea.

I prefer Silent Weapons Sound Mod but if you like the vanilla gunshots there's the collection of mufflers below, 50% is pretty nice. Silent Weapons Sound Mod is still too loud for my old vintage ears. 50% is my go-to now.