It's pretty simple to do what the title mentions. Just a few tweaks and then you'll be able to carry as many KGs as you want in S.T.A.L.K.E.R.: Shadow of Chernobyl.
ATTENTION: If you already have a mod installed in S.T.A.L.K.E.R., then you should have a "gamedata" folder in your game directory. If so, then skip the first three steps.
1st step - Download the .rar file from the link below:
In order to be able to change the weight limit, you must have a gamedata folder along with the "system.ltx" and "actor.ltx" files. Note that you need WinRar so you can open the folder from the link. It is free so you can download it easily.
EDIT: This stands as an alternate link for those who don't possess an account on 4shared:
2nd step - Move the "gamedata" folder.
Just move the folder found in the .rar to your S.T.A.L.K.E.R.: Shadow of Chernobyl game directory.
3rd step - Modify the "fsgame.ltx" file.
To make the game read the data from the gamedata folder, you just have to change a word in your "fsgame.ltx" file, found in your S.T.A.L.K.E.R.: Shadow of Chernobyl directory. Open it with notepad, and you should see something like this (without the quotations):
"$game_data$ = false| true|"
Just change the "false" statement into a "true" one, and it should look like this (without the quotations):
"$game_data$ = true| true|"
4th step - Start tweaking the "system.ltx" file.
Alright, now we can begin changing stuff from the "system.ltx" file. It's found in the "gamedata\config" folder. Open it with notepad then press Ctrl + F to search a word. It's easier like that, rather than searching something for yourself in the whole document. Alright, after pressing ctrl + F, write in "max_weight" (again, without the quotations). If the game isn't modded, then the "50" value should be next to that line. Well, that's the value of how much can your character carry before starting to tire. You may change it to whatever number you like. Let's say we put 100. After that, just close the file and save the changes.
5th step - Start tweaking the "actor.ltx" file.
Now there are still two changes that must be done before being able to carry as many KGs as you want. First, just open the "actor.ltx" file that can be found in the "gamedata\config\creatures" folder with notepad. Then press Ctrl + F again and search for "max_item_mass" (without the quotations). Next to that line, the "50" value should be input, if your game isn't modded. Alright, now you probably noticed the max_weight's value and the max_item_mass' value are the SAME. So you should input the SAME value to them both, otherwise it won't work. So if we put 100 to the max_weight's value, then we put 100 to the max_item_mass' value as well.
After that, search for "max_walk_weight" (without the quotations). The value next to it should be "60" if your game isn't modded, and it indicates how many KGs your character may carry before he won't be able to walk anymore. As you may have seen, this value is HIGHER than the other two values. So you should change it to a higher value too. If we input 100 to the other two, then we must put...let's say 110 to this one. Of course, you may put even 200 if you like, it's just that the number must be higher than the other two. After that, just close the file and save the changes.
And...there you go! Your character may carry a new amount of KGs. Whether it's a smaller value just to increase gaming realism or a higher one to increase fun, I hope this tutorial helped you.