This mod let you change textures, music, sounds and etc. How to download? Here's the link: https://modworkshop.net/mod/197
Then, after you downloaded, launch it and click on «options/about», then click «browse», and then specify way to the folder with your game. After that, we're going in «mods» and select mod. (To install mod first thing that you need is to add it, it must be .pdmod format). Then press «Apply Changes» button and wait until all mods get installed.
Here's some mods with BundleModder support:
https://modworkshop.net/mod/29262
https://modworkshop.net/mod/28989
https://modworkshop.net/mod/27420
And etc., I think you can find other mods yourself.
Mod author: Simon

This global mod probably the only one. Because, what mod adding is: anti-cheat system, optimization, bug fixes, New Difficulty OVERKILL 193+ (even hard than 145+), Skip Intro and also if you fall from the map, run around and this mod is back to map! So, how to download it? This time you need to go in this mod's official group in Steam (link here - https://steamhost.cn/steamcommunity_com/groups/dahm4pd/discussions/3/490123197956419203/)
And then after downloading, we have to extract all the files in the game folder. Launch the game, make sure it works and setup this mod as you wish. Okay, but «How to download mods for DorHUD?» Simply! Just install mods that DorHUD supports and extract them in «mods» game folder. Launch game again, press Options, then Mod Management and setup them too. (I don't seen some mods like noclip-camera in mod list, but it worked)
Here's a handful of mods that you can install for DorHUD:
https://modworkshop.net/mod/28437
https://modworkshop.net/mod/29161
https://modworkshop.net/mod/28062
https://modworkshop.net/mod/28066
Mod author: Dorentuz

That's all, I hope this guide helped you to understand how to install mods for PAYDAY: The Heist.
Bye everyone ;)