Rank 1 of the Lone Wanderer perk says it increases carrying weight by 50. Upon taking Rank 1, my character was able to carry 340 aided by her Deep Pockets mods. I was highly anticipating the moment when she could take Rank 2 of Lone Wander, because it proclaimed to increase carrying weight by 100. Whee!
Well, she just achieved Rank 2, and her carrying weight is only 390, not the 440 I was expecting. It appears that the 100 increase in carrying weight represents a total increase from one's base (50 from Rank 1 and an additional 50 from Rank 2) rather than an add-on (50 from Rank 1 and an additional 100 from Rank 2).
I'm wondering if I'm the only one who anticipated a total of 150 extra weight. 100 is nothing to sneeze at but, well, 150 would have been even better.