Yeah it can be altered by going into the game files but I suggest learning to pick and choose what you need on your ventures into the zone been able to carry 100kg+ gets very boring after awhile when you can carry a small army of guns and ammo with you. Later on a mod called Misery will test your Stalker skills to the limit.
I liked the weight limit - Autumn Aurora dropped it further (though not so much as Misery!). It makes you think about what to carry, specific load outs for different missions and stash management. Very much adds to the immersion.
Cheers,